Just got me new 383 to stop backfiring after a blown head gasket on a new motor. Now I am getting the gode for EGR. My friend semi tuned it with a off the net tune. Now my car is a 383 SC with a 6PSI pulley. The tune is from a SC car which is a auto (I have a M6)and all the stuff I DONT have. I elimated my EGR and a few other things. My car if I clear the codes it idles fine but as soon as it gets semi warm after say 2-3 minutes the idle starts going from 3-400 to 15-1600 and back and forth. I was wondering if the tune has anything to do with this or is it something else? If it isnt the tune then what are some things to check? also does anyone know where I can get the gasket on the BOTTOM of the throttle body? I think mine is leaking and I need to replace it. also the fuel pressure is right at 40 PSI at idle. And 1 more thing is when the car is idling funny I can shut it off, restart it (fires right up) then it revs to 1500-1600 then dies! I am getting really sick of all this mess but someone please point me in the right direction.

Thanks
Matt