on a cold start the car warms up properly and when its at ideal temp the idle is usually between 900ish in park and 500-600 in drive. now my problem is whenever i hot start the car the idle immedialy drops down to 600ish rpm in park and 400-500rpm in drive very low almost about to stall on me this never used to happen to the car it used to just idle normally. anyone have an idea what could be causing this, before the car started to hunt/surge like crazy but i found a broken vac line that fixed it. on random hot starts the car will idle like normal but thats rare now.

 

500 RPMs is the proper idle speed in drive for an LG4. This is the stock carb/distributor, correct?

Go through the basics - make sure no more vacuum leaks, no SES light (check the codes if there are, fix what needs to be fixed), set the timing to the proper advance, check and adjust IAB and TPS. When everything is up to snuff, set the curb idle speed to 500 RPMs in drive.

 

Yes 500rpm sounds about right while in drive but the problem is when I hot start the car the idle will be at 500-600rpm in park and in gear it'll be at the 500 or a little below it and that's too low. Before it would idle at 900 in p/n. It just started doing this recently I tried replaceing my egr in hope that maybe it was causing a vacume leak but all I could find we're positive aftermarket ones and it didn't change a thing once I replaced it so I went back with the stock negeative

 

Hook a vacuum gauge to your car and check for a leak. If the hoses are mostly original and you found one bad hose, it's likely there are other bad hoses. Also is this a problem that suddenly occurred, occurred gradually, or something that the car always did?

 

Is there a throttle kicker solenoid one the carb? is the high idle cam clear of the throttle stop linkage when you are setting it?

As 5-7 advised, check the IAB setting, but also clean the air bleed and throttle bores first.

 

yeah i think i figured out the problem. the ac compressor is stuck on for whatever reason so its drawing out power and lowering the rpm. now it dosent blow ac when its in the off position but the belt is moving and i can hear the it working. would a bad ac relay cause this to happen?