I have an 02 Jaguar S-type 3.0 liter with 86k on it. I bought the car cheap because the owner thought it needed new coils. What I found was the spark plugs were old so I replaced them, due to the fact you need to remove the intake manifold to replace the right side spark plugs, I found mismatched spark plugs. I also found moisture down in the plug wells on the 3 coils that were not firing. My solution was to replace all the spark plugs, clean and dry the coils and coil boots and apply WD-40 (water displacement - 40) liberally on the boots and in the boots. I put it all back together and it runs like a champ. No more check engine lights and no more stumbling and misfiring. So if you have the time to dismantle and inspect the coils and plugs its a good way to save some money. Or you can just replace the coils and hope the moisture doesn't build up again. Good Luck!

You have to replace the wires and something else that fire the plug the part is on every plug housing area. I have placed 4 in a year. I can't think of the name.