Horrible Performance, Can't figure it out!

[DJ Robu5t]

Afternoon Everyone,

I'm new here! I have a 2002 Mustang GT and frequent the forum for that one, but I just got this 89 Mercury Grand Marquis from a family friend. Has 40,000ish miles, was sitting for a year and a half under a covered drive way though. Started up fine when we first went to move it to my house, stalled out half way home, long story short it was the bad fuel and fuel filter. Changed all of that. Ever since then I've been changing things one by one trying to find the root of the problem.

Problem: Takes about 6-10 times of cranking it, tapping the gas a little bit. But eventually it does start and runs nice. It used to stall out when I'd press the gas, but we cleaned it all out and tuned it up, so now it runs fine and accelerates fine. However, when you let off the gas it will idle a little high for about 10 seconds (kinda seems like the throttle is sticky) and then it will drop off and idle really low, after about 20-30 minutes of idling it will stall itself out. It is also hard to start again once it's warmed up. I just took of the egr valve and cleaned it, it opens when a vacuum is applied to it, the car will almost stall, which means the valve itself is working. The egr vacuum solenoid is getting vacuum. I didn't check the dpfe because to be honest I'm not really sure how. I just took off the IAC and cleaned it. I'm at a lost and don't know where to go from here. I don't believe it's mechanical or anything inside of the engine because it runs fine and accelerates fine, just has a bad idle and is extremely hard to start. I obviously don't want to leave me girlfriend stranded so I want to fix it all and not have her stuck on the side of the road.

Thank you in advance for any help at all! and I'm glad to join the forum!

Rob

[gadget73]

sounds like the IAC is bad / sticky. Its the other thing on the side of the throttle body. Sometimes the aftermarket ones don't work so well. Also worth taking a look at the TPS for any damaged wiring, and checking it for codes. The check engine light comes on for almost nothing, so its very possible to have codes and no light. I'd also give it a full tuneup and be replacing all of the vacuum lines. If it sat long enough for the fuel to go bad, its entirely possible a critter got in there and ate some of the rubber. These things don't like vacuum leaks at all. Its also possible that the injectors are gummed up and need to be replaced but I'd put that as a last ditch effort in repair.

[Lincolnmania]

the hot stalling and not wanting to restart sounds like a heat soaked tfi module or a distributor pickup.......prob starts fine once it's cooled off some