I own a 97 f150 lariat with the 5.4, lately the engine has a miss in it but only at a certain rpm. i got a code p0304 (misfire on the #4 cylinder) This may sound strange and i usually am more compatant (sp?) about these things but i am having trouble getting to the plugs and plug wires....please help!!!! i read about the heater hoses leaking and causing moisture on the coil pack but figured i'd start with the plugs and wires (truck has 70K) also, i read about the rough idle and getting the wires off the ac accumator. what is the accumator and where do i find it to see if that solves my rough idle? any other info is welcomed. i've only had this truck 6 months. (mine too has the door cracks) Thanks Alot!

 

I had the same thing. Heater hose above the number 4 cylinder coil pack was leaking and dripping down on cylinders 3 & 4. Removal of the sparkplugs showed rust build-up around the spark plug metal base. The #4 coil pack had a hair-line fracture in the epoxy near the plug for the primary ignition wire. A new coilpack for $46.50 from my dealer solved the problem. Look for other messages on this topic by searching for "coilpack" or "coil pack". This is not an uncommon occurrence. By the way, passenger side cylinders are numbered 1-2-3-4 front to back and driver's side are 5-6-7-8 front to back.