Start car in the morning. Fires up, runs at higher idle for 30 seconds then drops down to 850 rpm or so. Idles fine for exactly 3 minutes then dies. Fire it back up and it idles low and rough. CEL comes on then goes off periodically. Let it warm up then take it for a ride. Runs like crap until the temp gauge reaches the halfway point then it runs pretty good, until I get to a stoplight. At that point, it idles low and rough. If I slip it into neutral the idle smooths out until I put it in Drive again. Sometimes it runs fine, other times like crap! I've replaced the IAC, MAF, fuel pump, fuel pump relay, cleaned and tightened both 10 pin connectors and also replace the ECU with a remanned unit.
66 - MAF below minimum voltage
87 - Fuel pump primary circuit fault
96 - Fuel pump secondary circuit fault
and today for the first time I got a new code
82 - Air diverter solenoid circuit fault
I was very careful installing the new MAF so as not to damage the heating element.
Seems to me if both the primary and secondary fuel pump circuits had a fault, the F/P wouldn't work at all!
I carefully inspected all the TAD vac lines and they seemed good.
I followed this procedure when cleaning the 10-pin connectors: Fuel Injection Technical Library Ľ 10-pin Connector Fix
I cleaned the 60 pin connector when reinstalling the ECU and ground all the paint away from steel when reinstalling the ECU ground screw.
Can a clogged TAD tube at the back of the engine contribute to the running problem and code 82 or would it be a failed solenoid?
Looking at the wiring diagram for codes 87 & 96 the wiring also runs through the inertia switch. Could that be an issue? All that's left besides that would be the wiring and various connectors.
I have no idea why it's still throwing a 66 code unless it's the wiring too. I know the harness is 25 years old but really??
I even took it into a shop I've been frequenting for 20 years and David, a very knowledgeable tech, threw up his hands and couldn't figure it out.
I'm kinda between a rock and a hard place right now. I plan to restore this Mustang but I need to get it running right before I tear into it! Ideas/thoughts/opinions........please!