i have a 94 del sol with a b18a, i took the engine back out to put a stage 3 clutch in when i put the engine back in it idles at 3,000 and drops back to 1,000 ect ect. switch some vac lines when the engine was out but i try moveing them around and nothing, if some one knows whats wrong or if some one has vac diagrames help

 

could be your IAC valve. Maybe you damaged it while taking out the motor and putting it back in.