i installed a new 350 crate motor from GM using all my old tpi stuff and now I am having minor problems getting the motor tuned. I first tried setting timing but it is hard to see timing mark on this motor since it is at 12o clock postion. The motor idles at about 900RPMS in N. I have disconnected the plug to set timing too. also, I took the car for a ride and it set a code for the MAP sensor. I put a brand new one on and still have a problem. could a over tightened knock sensor be a cuse of this. what about EGR valve, i bought a brand new one from NAPA and it came with about 15 different size slugs to put on the top of it the directions to me to get it as close to my old one as possible. my old one never have these slugs. is there a way to disable the EGR. could that be a prblem with my timing. THis is on a 1991 z28 350 tpi 6 spd