I have a 90crx, with a swapped rebuilt B18A1 Integra Ls motor in it. The motor runs strong and has about 90,000 total on it. But I am having an idle problem, see it never likes to idle in one place. When I push in the clutch when I am cruising, the rpms kick down to like 800, then rise to about 1500-1800 then it kicks back down, it does this over and over again while I am coasting with either the clutch pushed in or while in neutral. But when I come to a stop, the rpms stop bouncing up and down and usually settle somewhere between 400 and 700 rpms. It does this most of the time, but not all of the time but I can never really stick a pattern too this in order to figure it out. Maybe I have an air leak? An air house that isn't on the engine? I am new to EFI engines, before my crx I drove an 80 chevy half ton, with a built 350, on 35s. So ya I'm in a whole new game now, any advice would be appreciated

 

check for any vaccum leak. get a can of carb cleaner and spray it until you head a pitch change. clean out your IACV, which may be clogged.

 

Alright sounds good, whats an IACV tho?

 

sensor on back of the intake manifold near throttle body. 2 12mm bolts and 2 tiny hoses and a sensor clip.