B18c1 engine trouble HELP!!!

I drive 93 civic hb with b18c1(1995), Recently my car has been running very choppy. When i drive the car, the car tends to jump like it's goin to stall. When i'm in neutral, my RPM idles high between 1800 and 2000 then when i gas it, it rev high before it drop really low like its' goin to stall. I have to give some gas just to keep it from stalling. PPl said that it could be the IACV (idle air control valve) but I check that and it seems fine. I clean it and put it back but the problem still occur. But the exhaust is spiltting out white smoke and leaving black residue on the ground.

I think it might be Head Gasket, but i'm not too sure becuz of the smoke. But i don't see any oil leaking though. But i do see a bit of oil under the Tranny. I even checked the engine code but there was none.

Check your vaccum hoses. A vaccum leak will also cause the engine to "race". As for the smoke and black deposits, that sounds like a head gasket. The same deposits and smoke occured on my truck and after replacing the head gasket it stopped. Hope this helps out some.