How did the wiring to the coils look when you replaced it? I had to replaced the engine wiring harness to cure the ills my truck seemed to have from the day I got it. Nobody could ever seem to figure it out, including the dealer. I had a coil fail, replaced it and it failed again. I took a good look at the wiring and it was brittle and flaking off. After replacing the harness (not too hard) it has never run this good.