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!!

 

are you throwing any codes?

 

Sounds like the car isent getting enough power in the ignition system when its under a load. I woudlent know where to start with resolving that problem.

I had a smililar issue wile in an emergency half way home on a highway trip with my old truck. My mechanical fuel pump had died so I Jimmy rigged in an electrical fuel pump but instead of taking my power off of my battery directley I took it off a specific wire in my ignition so it would only work with the key on. Well, anywhere above 85kmh it would sputter, miss and die. Under was fine and easley accelorating was good too. I took it off the wire that went to the coil somewhere along the line. 85kmh for the remaining 350km of a 1000km trip kinda sucked but my mialage was great!

 

No codes at all, wish it would throw something...

How likely is it to be a fuel pump?

 

check the ohm's in your coil pack

 

Is there any other way to test this other than a multimeter? My MM is on my boat 100 miles away.

I might just go buy a cheap one. Would I just check from the each of the 6 "coils" to ground?

 

How are your connections going to your coil?

 

You mean plug order?

 

no, i mean take them off one at a time and see if theres gunk in there.

 

All looks good, no gunk and shiny terminals, both coil and plug wires.