Ok my timing belt slipped off my car weeks ago and the belt slipping off caused 5 valves (intake) to bend.. Instead of replacing the valves I went ahead to pick n pull and got a used cylinder head w/ good valves and replaced it for my old head.. I put it all on, got the timing marks right and started the car and in neutral it didnt really want to start so I put it in 1st gear and it started right up.... but it immediately revved up to around 3-4.5 RPM's and stayed idling right there.. When I 1st replaceed the head i put the head gaket on backwards but i redid it again and put everything on right and now this idling problem... Also when I let it sit for a while smoke would come from the Exhaust Headers maybe because I lost a few bolts and the exhaust headers is missing about 2 bolts in it.. Ive been told it was a vacuum leak but not sure on what to do or expect any help please?