Engine Performance problem
1997 Ford F150 V8 Four Wheel Drive Manual 135000 miles
the 4th cylinder is missfiring in my truck. When I first driive the truck it runs fine for the first couple of miles, then it starts to missfire. I have tested both coil packs, replaced all plugs and wires, and run fuel system cleaner regularly. Sometime it will be missing the starts running great again. Some times it idles fine other times it dosenot. Any sugestions?