PRELUDE IDOL PROBLEM. revs up and down rapidly..

Hey,

I have an 89 prelude Si2.0l. b2015. 5speed

When it tries to idle it revs up to 1500rpm then falls rapidly to 1200rpm and back up and down rapidly, then finally falls back to around 850rpms...it's extremely annoying, it sounds as if i'm reving my engine. I've changed the acual idle and such, but it just keeps doing it. if i turn the idle all the way down, the car makes a "whistle" noise when accelerating, but still revs up and down when trying to idle anyways. Does anyone know what this could be, or how to fix it...

I've reset the computer many times, and all that.

Thanks.

check post on "idle problem" i will reply on it to place it on page 1. common problem on old honda's.