could this be my iac?

[newbieMX3]

I have been having the bouncing idle problem once the car is warm, it bounces from 1000 to 1500..... i cleaned my throttle body which was pretty dirty but that didnt eliminate the issue. I can get it to stop bouncing and hold steady if i play with the clutch a little while sitting still. If i let the clutch out a little bit the idle stops bouncing and stays steady at about 900 rpms.........
so what do i do? its driving me crazy!!! could it be anything else?

[umcamara]

Check for vacuum leaks.

Go now!!

[Nd4SpdSe]

pcv valve

[davmac]

You're just putting a load on the engine by riding the clutch - so it is no longer idling. Once your car has warmed up to normal operating temp the IAC is adjusting air and indirectly idle speed based on temperature seen by the thermosensor at the front left (nearest cylinder 2, 4, 6) side of the engine. If the sensor is bad or coolant is low (so the sensor is not completed submerged in coolant) then the idle willl be erratic. It could also be vacuum, but bad vacuum will effect idle even when the car is warming up.

[vansolrick]

Interesting. I've always had a similar problem ever since I got my car in late December. I fixed it a little bit when I changed out my TB but it's still doing it, just not as drastic. I think that cleaning the vacuum lines, IM, and replacing the TB with a polished one helped a little bit, but my idle is still doing what the OP stated. I'll check my lines again, and I'm thinking that it could be a sensor since my idle calms down once the engine is warmed and running at operating temperature.

[tmac4t4]

my car's doing the exact same thing...after wondering why my car was barely idling at around 300rpm i noticed the iac screw on the top of the throttle body was closed all the way,,after adjusting that and setting the rpm where it should be, the car now constantly bounces from 1000 to 1500 rpm once its warmed up ?? what could be causing this?