For some reason here in the last month or so my idle has been jacked up. When I start the car it does its normal surge and once it warms up it has a steady idle of 850 or so and does fine, it will go back down at a stop light or what ever but then after like 15 min or driving it will only idle ot 1500 or so and not come back down...its annoying the hell out of me. I cant figure out what would cause it. Maybe a vac leak? But wouldnt the idle be messed up the entire time? The idle adjust screw on the TB? But again, it would be high from start up. One other thing is...can having a cut out effect anything like this. Maybe the engine gets confused on the airflow or backpressure?? I know thats dumb but I dont know. I have a new TPS on it, I do have the shitty fast 90TB but I dont think its that. I have a SLP 85maf but again...that shouldnt mess with the idle like that. Guess I'l change out the IAC and see what that does.

 

I would guess the IAC as well

 

ls1 and idle... two that dont mix

 

I beleive this is the second post that I have seen from you concerning problems. I really think you may have tuning issues.