2003 Won't idle when hot

[NScarpi]

I have a 2003 ZX3, 109000 miles. I have maintaned it well. It runs great but 3 weeks ago I start having a problem with it idling. I was in rush hour traffic, pulled into a gas station for a coke. When I came out it wouldn't idle, I had to keep the rpm's up when stopping, but after 5 miles or so all was back to normal. Since then it has happened 3 more times with today being the worst. It would die if I was driving and took my foot off the gas. The check engine light is not on. It has been 85 to 95 on the days that this has happened. I looked at the fuel lines in the engine compartment and they are not laying on anything hot. It seems fine unless I shut it off for a short time and then restart it. I'm guessing some type of vapor lock. Today after it happened I drove it for 10+ miles and as long as I wasn't idling it was fine, full power, no sign of a fuel problem. Just wouldn't idle. Has anybody run into this before?

Thanks
Nick

[Davescort97]

Check for a vacuum leak. IAC may need to be cleaned or replaced.

[NScarpi]

I don't know what the IAC is, is it the idle air control? Please let me know and I will check it. Checked for Vacuum leaks didn't find any.
Thank You For your Help
Nick

[Davescort97]

The IAC (Idle Air Control) controls the idle speed when load inducing accessories are turned on like A/C and Alternator loads. It increases the idle speed to compensate for the extra load. It does this by putting extra air in the engine with the IAC. It may need to be cleaned or replaced. It is a small electric motor connected to a flange on the top of the Throttle Body. It has 2 8mm head bolts and has a couple of wires going into it.
Take it off and spray the inside of the IAC cavities with choke cleaner spray. Let it soak for a while and then spray it again. Lubricate the pintle between the cavities with a light engine oil. Put it back together and you're done. If this doesn't help you will have to replace it.