My 1999 F-150 4X4 5.4 (103K Miles) stutters like it has bad gas. I do not have any codes showing. I replaced the fuel filter and the spark plugs. It doesn't seem to happen until the engine warms up. Normally takes place around 15-2000 RPM and doesn't feel like (as harsh) like an electrical miss...more of a stutter. I ran two cans of water remover through and am down to 1/8 tank. Did I read somewhere an ERG valve might cause this? Any help would be greatly appreciated.

 

Took truck to Ford dealership and it turns out the #4 COP is bad. $231.00 parts and labor. The reason I didn't suspect the COP's was I had the #4 replaced by dealership about 6 months ago (oddly enough) and it really MISSED not stutter. Oh well lesson learned on new parts. Oh by the way, I replaced the plugs last weekend attempting to fix the problem and the fact it had hit the 103K mark. Visually there appeared to be nothing wrong (burnt marks, cracked boots, etc.) with the COPS. Plugs are a bear to change as you know.

 

If the COP was replaced only 6 months ago would it not be replaced under warrenty.

Rick

 

Your are correct I believe. Because it is a different Ford dealership that performed the work this go aroung I will attempt to locate the old paperwork and try to get some bucks back. Thanks

 

I have a 2001 supercrew with the 4.6 and had the stuttering twice, the first time only after 20K, #4 was bad so they said. Warranty covered it. Second time was at 100K. Since it wasn't under warranty anymore, took it local mechanic/non dealer. All he did was replace the rubber boot. He mentioned that was a big problem with the Coil over Plug. Runs great now. Another problem is dirty injectors. Get those cleaned often.