Idle problem
 

A friend of mine has an 87gt with an idle problem. When cold, it cranks and the idle rises to about 2k and then falls to about 500. This cycle repeats itself a few times until the temp starts to rise. Once it warms up, the problem goes away. Like if he stops at a store, when he comes back out, it acts fine. I was thinking EGR, but I would like a second opinion. If anyone has any useful info, it would be greatly appreciated.

Caymon

try replacing the IAC, if you dont want to buy one, find another mustang guy and switch it, it takes like 5 min... remember to unhook the battery for 10 min... that could be it! ive had a shiza load of Idle problems, and i still do! lol... i just drive it like it is.

i would say either the iac or the egr valve