!PROBLEM! Mustang won't idle


New Member
Apr 11, 2005
Hey everyone. I am having a problem with my '96 GT. Basically, when I start it up the engine revs but then the RPMs immediately drop and the car dies. I can keep it going by keeping my foot on the gas but as soon as I let off the RPMs once again drop and the car dies. I drove it like this for about 20 mins and halfway through the drive it started to idle although at about 500 RPMs, it wasn't dying though. Do any of you know what could be wrong? This happened before and I thought I fixed it by changing the fuel filter. After I did that it worked for another few months before this started happening again. Thanks!

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Give your IAC a good cleaning since it's failing on you.

If cleaning it doesn't help, then you'll need a new one :nice:
Also, if it doesn't want to start, you can give the IAC a tap with the handle of a screwdriver. That will usually loosen it up and allow you to drive without any problems until the engine cools down. Just a temporary solution until you purchase a new one.
Yes the Idle motor is the most likely problem, clean it out and reinstall it. While you're at it hose out the throttle body as well. There could be another issue, but it's probably unlikely in your case. The A/c switch located on the pass side rear of the engine compartment could also be acting up. This could be from a low freon level. The symptoms are similar, which is erractic idel, if the freon is OK then (if it's as tock switch) there is an allen screw inside it once you pull the electrical plug off, try screwing it in (or maybe out, it's been awhile) and this will adjust the sensitivity of the switch. Or you could just replace the idle motor and/or the a/c switch. Anyway, start with the idle motor.
dude its deff. the iac (idle air control motor or valve) what happens most of the time oil,carbon and dirt most of the time build up on the pintle inside and stops it from sliding the valve back and forthto let the required air to keep the engine at idle. other times but rarely the electronics go bad inside of it so dont waist your time cleanig that peice spend your money and buy a new one, spend a little more and get a quality peice from ford, cause theres 50/50 chance afer cleanig that itll work for awhile if not at all, and yea use a good intake cleaner to clean the throttle body
I agree with everyone ....

On my B4000 (Ranger), it started acting crazy like how you described your car is running and it turned out to be my crankshaft position sensor. But it threw a CEL and that's how I knew it was that sensor. So if you aren't getting a check engine light, it's either your IAC, MAF, TB, etc., but most likely your IAC.
Are you all (those who have replaced their IAC), buying them from Ford or aftermarket and how has your luck been?

When you say cheap, how much are they? For my truck they are pricey ...
I have a '96 GT as well and I experience this same exact problem.. Mine only happens very sporadically (maybe once or twice a month). And just like you in order to drive it I have to put it in neutral and give it gas in order for it not to shut down.. Usually after about 15-20 minutes it "fixes" itself and drives normallly. Or when it does this I'll just leave it off and come back in like 20 minutes and it starts right up like nothing ever happened.. I just replaced my IAC about 1.5 years ago, could it be bad again already?