I had a similar issue with my jeep. There was a valve spring that snapped in half. Run a diagnostic to see which cylinder is misfiring and check the spark plug for any dings/dents. We found damage on our spark plug which told us something inside was busted. It was a lot of frustrating work but she purrs like a kitten now.
I've been trying all day to send you a post from 630 am okay first 1x1 take out your coils and inspect the boots take them off the coil and roll them between your fingers looking for cracks at the bottom of it next if they feel real soft and mushy they must be replaced because they develop tiny micron holes that you can't see letting out + voltage to - engine ground = misfire next while taking them out look for moisture on the boots if there is and your running on antifreeze but you find water your inner fender splash guards are either broken or missing, and water from rain or high pressure car wash's is entering the spark plug chambers=misfire , next take out your spark plugs if they are worn down this will = misfire , but also if the plug is in good shape and you check the air gap between the firing pin and the ground electrode and its to far apart= misfire this is because when the engine is cool to medium hot maybe 15mins. it will run fine but as increased engine load happens engine temperature goes up and as we know from science class metal expands when heated so that electrode at the base of the plug is now moving away causing even more air gap = misfire ,next while you have each coil still out inspect [a]the plug on top where the connector goes into look for cracks in that top area if = misfire also look inside it at the 2 prong contacts any corrosion inside will again =misfire, next grab the coils firing spring firmly a the top of it and at the very coil bottom and pull it out to see the coils firing contact any blueish green oxidation or corroded white powder or any other matter = misfire , you can clean these with alcohol and ladies emery boards trim it down to fit and LIGHTLY WET SAND IT WITH THE ALCOHOL AND FINSH WITH CONTACT SPRAY TO FLUSH OUT DEBRI THE RE-ASSEMBLE IT next also pay attention to the clips on the coils connectors if those tabs are broken = misfires because from normal engine vibrations these can move back n forth and cause that to happen you can use wire/zip ties to secure them till you can get new plugs, next I typed this so many times today its incredible I didn't smash something from aggravation with this sites posting anyway when you are checking those coil boots for moisture and you find antifreeze in the chambers and its only on the thermostat side your gasket is leaking or the crossover that the thermostat is installed in is cracked or the whole gasket underneath it is no good and the intake must be removed to correct this same if you find antifreeze on both sides that crossover gaskets are leaking from under the manifold= misfire next , if you should find anti freeze on the bank#1 [passenger side of engine] but its in one cylinder and not another EX. #2 but 3/4 are dry or #2 and 1/3/4 are dry you have a cracked head and the same goes for bank #2 if #5 is wet and 6/7/8 are dry or 7 is wet and #'s 5/6/8 are dry same thing ok I have to tell you all of this so A. you learn about the possibilities and B . so you don't go out and spend$$$$$$$$$ and find out in the end that your pretty much screwed, So I covered everything here and the same applies for oil except that it could be the valve cover leaking and on the oil fill side you could've spilled it putting it in but if your seeing blue smoke on a cold engine start there's oil leaking into the cylinders or the valve seal are bad = puff of smoke after idling and you pull away and there's a blue/white cloud behind you these are all the common problems with these 4.6 Romeo/Windsor engines and 1 more thing if you try to take out the spark plugs and it won't budge STOP use liquid wrench to soak the plugs for 2hours or more to help loosen them these motors are know for snapping plugs in the plug chamber because the person who changed them before didn't use anti-seize lubricant on the plug threads and the pugs bake themselves in from a year of engine heat and especially if your running hotter than normal ok be very careful trying to take them out if you have to keep spraying them till you see the lube level go down do it you'll thank me later for listening to what I said here okay and just so you know where this info is coming from I'm a taxi mechanic in NYC.with 50+years of experience in all phases of the automobile and from about 1985 are fleet of 300 cars has been fords and lincolns and mercury and I must have rebuild 25,000 of these motors since around,1990 but don't misunderstand these are great engines and last till about 470,000 miles till they need a rebuild and in taxis that' about 2 1/2 years so if you do it right it will last a real long time on a civilian vehicle and now you know everything save this post good luck to you and anybodyelse who reads it Stephen
Answers & Comments
I had a similar issue with my jeep. There was a valve spring that snapped in half. Run a diagnostic to see which cylinder is misfiring and check the spark plug for any dings/dents. We found damage on our spark plug which told us something inside was busted. It was a lot of frustrating work but she purrs like a kitten now.
I've been trying all day to send you a post from 630 am okay first 1x1 take out your coils and inspect the boots take them off the coil and roll them between your fingers looking for cracks at the bottom of it next if they feel real soft and mushy they must be replaced because they develop tiny micron holes that you can't see letting out + voltage to - engine ground = misfire next while taking them out look for moisture on the boots if there is and your running on antifreeze but you find water your inner fender splash guards are either broken or missing, and water from rain or high pressure car wash's is entering the spark plug chambers=misfire , next take out your spark plugs if they are worn down this will = misfire , but also if the plug is in good shape and you check the air gap between the firing pin and the ground electrode and its to far apart= misfire this is because when the engine is cool to medium hot maybe 15mins. it will run fine but as increased engine load happens engine temperature goes up and as we know from science class metal expands when heated so that electrode at the base of the plug is now moving away causing even more air gap = misfire ,next while you have each coil still out inspect [a]the plug on top where the connector goes into look for cracks in that top area if = misfire also look inside it at the 2 prong contacts any corrosion inside will again =misfire, next grab the coils firing spring firmly a the top of it and at the very coil bottom and pull it out to see the coils firing contact any blueish green oxidation or corroded white powder or any other matter = misfire , you can clean these with alcohol and ladies emery boards trim it down to fit and LIGHTLY WET SAND IT WITH THE ALCOHOL AND FINSH WITH CONTACT SPRAY TO FLUSH OUT DEBRI THE RE-ASSEMBLE IT next also pay attention to the clips on the coils connectors if those tabs are broken = misfires because from normal engine vibrations these can move back n forth and cause that to happen you can use wire/zip ties to secure them till you can get new plugs, next I typed this so many times today its incredible I didn't smash something from aggravation with this sites posting anyway when you are checking those coil boots for moisture and you find antifreeze in the chambers and its only on the thermostat side your gasket is leaking or the crossover that the thermostat is installed in is cracked or the whole gasket underneath it is no good and the intake must be removed to correct this same if you find antifreeze on both sides that crossover gaskets are leaking from under the manifold= misfire next , if you should find anti freeze on the bank#1 [passenger side of engine] but its in one cylinder and not another EX. #2 but 3/4 are dry or #2 and 1/3/4 are dry you have a cracked head and the same goes for bank #2 if #5 is wet and 6/7/8 are dry or 7 is wet and #'s 5/6/8 are dry same thing ok I have to tell you all of this so A. you learn about the possibilities and B . so you don't go out and spend$$$$$$$$$ and find out in the end that your pretty much screwed, So I covered everything here and the same applies for oil except that it could be the valve cover leaking and on the oil fill side you could've spilled it putting it in but if your seeing blue smoke on a cold engine start there's oil leaking into the cylinders or the valve seal are bad = puff of smoke after idling and you pull away and there's a blue/white cloud behind you these are all the common problems with these 4.6 Romeo/Windsor engines and 1 more thing if you try to take out the spark plugs and it won't budge STOP use liquid wrench to soak the plugs for 2hours or more to help loosen them these motors are know for snapping plugs in the plug chamber because the person who changed them before didn't use anti-seize lubricant on the plug threads and the pugs bake themselves in from a year of engine heat and especially if your running hotter than normal ok be very careful trying to take them out if you have to keep spraying them till you see the lube level go down do it you'll thank me later for listening to what I said here okay and just so you know where this info is coming from I'm a taxi mechanic in NYC.with 50+years of experience in all phases of the automobile and from about 1985 are fleet of 300 cars has been fords and lincolns and mercury and I must have rebuild 25,000 of these motors since around,1990 but don't misunderstand these are great engines and last till about 470,000 miles till they need a rebuild and in taxis that' about 2 1/2 years so if you do it right it will last a real long time on a civilian vehicle and now you know everything save this post good luck to you and anybodyelse who reads it Stephen
Your welcome and I meant 2,500 motors just to tired good luck