Missfire from idle to aprox 3000rpm

[shifterpilot5.0]

I have a missfire from idle to around 3000rpm except when WOT. The tach is not jumping so I know its not connections, the wires are about a year old ford motorsport.(could be breaking down) The spark plugs are lean looking(look like they have gotten heated up alot but very clean) Car acts like its getting too much fuel(loading up) No smoke at all comeing out of the pipes. I have checked tps, timeing, mass air meter, fuel pressure reg, no vac leaks. Just started this after i filled up the tank( mabe bad fuel?) Runs awesome at WOT. Any suggestions? O-yeh its a 89 gt 5.0 with a 5 speed trans

 

[MagnaflowGT]

try adjusting ur alternator. Tighten the little bolt on it. I had the exact same problem. I had to get a new alt, because it damaged the old one bad. Ever since, havent had a problem, and she purs fine through all tach levels..

 

[HISSIN50]

Any codes?

 

[shifterpilot5.0]

No I have tried to put a code reader on it and it wont respond. I think the computer has been replaced with a different year? It wont work.

 

[Bottomlesspit]

The inability to get codes doesn't sound good. Being an '89 the computer should be a basic swap for most years 88-93. Unless the previous owner did some hanky panky stuff with the wiring and computer......???
Based on the parts you have already swapped or checked, there is one more you might consider. The TFI module there on the front of your distributor. My car developed a similar type miss, and only at certain rpms AND a certain throttle setting!!! I finally took it to the Ford dealership and they found an "intermittent" TFI module. They told me it was not uncommon for these modules to develop a "soft" spot where a certain rpm range might get blocked out and cause problems. Indeed, a new module did fix the problem.
Just another item you might consider.
Good luck,
Ken

 

[shifterpilot5.0]

Thanks, I didnt think of that. I have an extra one I will slap it on and see if thats it. I dont like to be a parts changer but you gota do what you gota do.

 

[shifterpilot5.0]

ttt