There are a lot of possibilities here first clean out the fuel injection and change the filter as a rule out cause next and this is where I think the problem is your distributor cap and rotor are severely worn and your plugs are out of gap and possibly your wires are leaking through the insulation ///// you stated that it runs ok until you drive it down the road well this is increased load and rpm's and if the plug gap is out or rotor and cap contact gap is out (to much wear on the rotor tip and the cap contacts for each plug) there is an electrical contact loss from to much air gap and this will cause your problem for sure as the rotor spins faster it can not maintain the demand so it misses and starts bucking because it's making and loosing contact as the rpm's go up and down give the Ole girl a full tune up here plugs wires cap rotor fuel filter and some quality fuel and injector cleaner and think about it the trucks needs maintenance and is 28-29 years old now by door sticker build date so you have to keep up on these things otherwise she's gonna leave you on the side of the road waiting for the hook and this increases your cost for the same remedy
Dave the throttle position sensors contact can be worn at the position right after idle rpm's and what I mean exactly is that when you start it the motor is at fast idle to warm up and then rpm speed gradually decreases to regular curb idle in park then you shift into drive and the idle speed lowers again about 50-100 rpm's and it's in between that area there could be a worn dead spot in the sensors contact that could be causing the problem you start to drive and it's okay till you get to that point in the sensors contact that the havoc starts and that is intermittent contact and voltage breaks on/off which causes the bucking because then it's running and then it's not then it is again so the engine is struggling to stay running and the Volare loss is in a split second and then regained and lost again also you could've received dirty fuel/water in it put 2 cans of Berrimans B12 Chem tool fuel system cleaner in the tank and fill up with 93 octane and also spray out the throttle body your truck is obd 1 and there should be a code in the system if you can get a read out autozone will do it for free or a mechanics scanner has both systems in itbut you can do this yourself with a jumper wire and a test light please go to 2 car pros.com/articles/ford-lincoln-mercury-obd1-1995-and earlier-diagnostic-trouble-code-definition-and-retrieval to get the procedure and the diagram of where to use the jumper wire and test light//// I searched ford obd 1 code extraction method and the 2 car pros article came up okay I haven't done obd 1 in over 20 years so I couldn't remember the pin locations in the connectorDave the throttle position sensors contact can be worn at the position right after idle rpm's and what I mean exactly is that when you start it the motor is at fast idle to warm up and then rpm speed gradually decreases to regular curb idle in park then you shift into drive and the idle speed lowers again about 50-100 rpm's and it's in between that area there could be a worn dead spot in the sensors contact that could be causing the problem you start to drive and it's okay till you get to that point in the sensors contact that the havoc starts and that is intermittent contact and voltage breaks on/off which causes the bucking because then it's running and then it's not then it is again so the engine is struggling to stay running and the Volare loss is in a split second and then regained and lost again also you could've received dirty fuel/water in it put 2 cans of Berrimans B12 Chem tool fuel system cleaner in the tank and fill up with 93 octane and also spray out the throttle body your truck is obd 1 and there should be a code in the system if you can get a read out autozone will do it for free or a mechanics scanner has both systems in itbut you can do this yourself with a jumper wire and a test light please go to 2 car pros.com/articles/ford-lincoln-mercury-obd1-1995-and earlier-diagnostic-trouble-code-definition-and-retrieval to get the procedure and the diagram of where to use the jumper wire and test light//// I searched ford obd 1 code extraction method and the 2 car pros article came up okay I haven't done obd 1 in over 20 years so I couldn't remember the pin locations in the connector
Fuel pump, Bcm module ,oxygen sensor )blocked injector, timing out ( needs to go on computer ) with a cable ombd1 or ombd2 ..It really depends on how old the truck is . other wise im just guessing. cheers
If you can eliminate that you don't have a fuel issue, I would look to the ignition system. If the cap & Rotor are in good shape, I would change the module. And have the parts store check it before you leave. I have found many of them bad out of the box.If you can eliminate that you don't have a fuel issue, I would look to the ignition system. If the cap & Rotor are in good shape, I would change the module. And have the parts store check it before you leave. I have found many of them bad out of the box.
Answers & Comments
There are a lot of possibilities here first clean out the fuel injection and change the filter as a rule out cause next and this is where I think the problem is your distributor cap and rotor are severely worn and your plugs are out of gap and possibly your wires are leaking through the insulation ///// you stated that it runs ok until you drive it down the road well this is increased load and rpm's and if the plug gap is out or rotor and cap contact gap is out (to much wear on the rotor tip and the cap contacts for each plug) there is an electrical contact loss from to much air gap and this will cause your problem for sure as the rotor spins faster it can not maintain the demand so it misses and starts bucking because it's making and loosing contact as the rpm's go up and down give the Ole girl a full tune up here plugs wires cap rotor fuel filter and some quality fuel and injector cleaner and think about it the trucks needs maintenance and is 28-29 years old now by door sticker build date so you have to keep up on these things otherwise she's gonna leave you on the side of the road waiting for the hook and this increases your cost for the same remedy
Dave the throttle position sensors contact can be worn at the position right after idle rpm's and what I mean exactly is that when you start it the motor is at fast idle to warm up and then rpm speed gradually decreases to regular curb idle in park then you shift into drive and the idle speed lowers again about 50-100 rpm's and it's in between that area there could be a worn dead spot in the sensors contact that could be causing the problem you start to drive and it's okay till you get to that point in the sensors contact that the havoc starts and that is intermittent contact and voltage breaks on/off which causes the bucking because then it's running and then it's not then it is again so the engine is struggling to stay running and the Volare loss is in a split second and then regained and lost again also you could've received dirty fuel/water in it put 2 cans of Berrimans B12 Chem tool fuel system cleaner in the tank and fill up with 93 octane and also spray out the throttle body your truck is obd 1 and there should be a code in the system if you can get a read out autozone will do it for free or a mechanics scanner has both systems in itbut you can do this yourself with a jumper wire and a test light please go to 2 car pros.com/articles/ford-lincoln-mercury-obd1-1995-and earlier-diagnostic-trouble-code-definition-and-retrieval to get the procedure and the diagram of where to use the jumper wire and test light//// I searched ford obd 1 code extraction method and the 2 car pros article came up okay I haven't done obd 1 in over 20 years so I couldn't remember the pin locations in the connector
thanks ill try that sound like you hit it on the head
Check and clean the throttle body and scan to see codes may have bad throttle position sensor
Fuel pump, Bcm module ,oxygen sensor )blocked injector, timing out ( needs to go on computer ) with a cable ombd1 or ombd2 ..It really depends on how old the truck is . other wise im just guessing. cheers
How long since it had a new fuel filter?
If you can eliminate that you don't have a fuel issue, I would look to the ignition system. If the cap & Rotor are in good shape, I would change the module. And have the parts store check it before you leave. I have found many of them bad out of the box.