ok so ever since I did the 2.3l manifold and throttle body swap my z24 has been idling at 2000 rpm. there are no vacuum leaks and ive got a feeling its got something to do with the idle air control valve but ive tried replacing the IAC from the 2.3 throttle body with the IAC valve I had on before because I knew it was working but is there a special way to install it? also the car holds rpm once I start accelerating like ill rev to 3000 go to shift and it just stays at 3000 until I let off the clutch and mechanically slow it down. then when im coming to a stop it will rev to like 3-3500rpm until I hit 10KMH and then jjust drops back to its high idle of 2000 rpm. I need to rewire an obd port as the one in the car has a lose connection and wont connect to the scan tool sooo before I get that fixed anyone have any ideas on what it might be?

sounds to me like a vacuum issue.