strange idle problem

[906000pos]

My car is running much better since my last post, howerver I'm still having issues with idle. On cold start ups the car seems okay, a bit rough but otherwise fine. When the engine is warm however it idles great until you move the throttle. If you are driving at a constant speed or if you rev the engine, when you release the throttle the idle is extremely rough for about 15 seconds then it levels out. I have cleaned the throttle body, IAC, and PCV valve and set min idle speed. The funny part is when setting the min idle speed with the IAC all the way in and disconnected the car runs perfect. The IAC appears to be fairley new, so I don't think it is bad. It is almost as if the car is not getting enough fuel as the IAC opens to increase the idle speed.

Any suggestions??????

[ctesla]

is this a 4cyl?
I didn't see your last posts.
do you use A/C alot?
the fieros, and others, with 4cylinders in mid80s-90s constantly reported that the A/C robbed the engine, and would cause idle problems after momentarily coming of full (or harder, steadier) throttle.
there is a cut off switch in the emissions system, that allows EGR to open in throttle conditions, and the four cyl. hits a dead spot;
then after acceleration, you have a momentary surging or hesitation, as idle returns.

A company called Sun Ray Co.
Fridley, MN

makes a product: Reg-Rite
which taps into the vacuum control regulator line and smooths idle.

(to isolate your problem first, just pull the vacuum line of the EGR and run the car unhooked to see if there is a pick-up in power, and proper idle)
because I could be incorrect, and you might just need a fuel filter (4cyl), or fuel filter & regulator (if it's a V6)

hope this helps,
ctesla