ok ive got a 2000 civic si with an idle issue, when its cold itll idle alright, when it gets warm itll idle to 650, try to pick itself up to 900 then sometimes drop close to zero then pick itself back up to 650. usually after a rev it stops at 900 for a split second then drops a lil below 650 then picks itself up to 650. ive cleaned the iacv and the throttle body, what else is possible?

 

More information is needed.

Is this problem associated with any recent work done on the car?

Any CEL codes?

Any disconnected or leaking vacuum hoses?