I just installed my old stock motor in my car. My other motor which what turboed was just taken out to be rebuilt. After installing my old motor back in, here are the symptoms: Smokes a little after starting in engine bay, black sut spitting out of exhaust, irratic idle (between 800 and 1200rpms).
Please help me out.

 

what color smoke?

 

the smoke is white/grey

 

The smoke in the engine bay could just be burn off, maybe you spilled some oil or coolant on the manifold, or a hot spot on the block, or maybe you have an exhaust leak where the manifold and cat connect. Try to calm the idle down using the screw on the throttle body.

 

Think i fixed it .
I used compressed air to spray the connections for the harness on the radiator, then the connections on the IACV. I reconnected them both. Started the car and the car ran a little bit better. I then disconnected the map sensor plug and the car turned off, (i thought to myself maybe I should not have done that), i then sprayed the connections with compressed air and plugged it back in.
I started the car again and it idled perfectly.