All rite i got a 87 mustang gt 5.0. Anyways The idle has been acting up. It revs at about 800 rpms, idling fine then all of a sudden it will rev up and down for a bit then idle fine. It does it off and on. I checked the tps voltage its at .98. Couldn't find any vacuum leaks. Any idea what it could be?

Thanks,
Ben

 

Did it just start doing it or did yu do some mods and then it started? Does it do it with the a/c or defroster on and off?

 

It did it a little bit after intalling a trick flow intake. I removed the ac. Anddoes it with defroster on oroff.

 

check the IAC

 

Or the EGR.

 

I checked the IAC by unpluging it while running and the engine died so i think it is good. Where is the egr located and how to i check to see if its good?

 

egr wont effect idle unless its leaking

 

more than likely a bad ECT sensor

 

The IAC shouldnt matter, even though people says it does, i ran my car without it plugged in and it ran fine, and i know othe people have to. THe egr is the big ugly thing on the back side on the TB, here s link if you need some help to find it
www.fordfuelinjection.com

 

Double check for vacuum leaks! I had one one time on my car and it turned out one of the metal tree pieces under the intake cracked. Rather than welding though I siliconed it