I have been trying to pin point a problem in my fiance's 01 mustang for a few weeks and seem to be getting nowhere. It is an 01, 3.8L, Auto, with 89k miles. It runs really rough, missing while accelerating and while under load. It does seem to idle ok though. So far, I have replaced the plugs, wires, PCV valve, fuel filter, and air filter. I also sea foamed it about 3 weeks ago and it seemed to help a little but now it's getting worse. What else could this possibly be? I don't mind spending money on it, but I don't to just start replacing random things on a whim.
Please help!!
Please help!!