Why does the engine in my. 1990 integra. The rpms race up to 2500 then down to 1000 rpms when the engine is cold. It goes away after the engine warms up.

 

I would go ahead and clean the iacv and fitv, if that doesn't fix your problem, then i would search for a vacuum leak.

Are you sure it doesn't bounce when it warms up? not even a little bit?

 

Also does it stay at 1000 rpm even when its warmed up and at optimum temperature? 1000 rpm is pretty high for a up to temperature motor, no? I know my motor after being warmed up goes from idling normally at 600-700 rpm to randomly jumping and staying at 1000 rpm which in result disables my vtec...

 

i had the same problem..mine idled like at 900k almost 1k..cleaned the iacv (behind the intake manifold) with brake cleaner threw it back on then POW! nice low idle..600-700k