On my 95 integra when i start it from cold, or even if i leave it sit for a hour or two. The RPMs blast up to 2200-2600, it will finally calm down to a normal 700-800 after it sits and runs for a few minutes (3-4) what could be doing this? A vaccum leak? I really don't know and it is rather frustrating and embarrassing sitting in a parking lot and your car sounds like its ready for "take off". The engine is an B18 LS/Vtec.

 

believe it or not.. when you do a cold start-up... it will idle higher than normal and gradually lessen as the engine heats up