First off thanks to every ones post on here that have helped me out over the last couple years. I just got my ls1 engine assembled and in the car, its a 92 z28 if that matters any. But the engine is fresh, prc stage 2.5 5.3 heads with howards asa cam and comp 1.8 rockers. cam specs are 226/236 and .525 lift before the 1.8 rockers. I had this set up before the rebuild but i had a timing chain pin walk out and wiped out my engine. Before the chain went i had the car running and driving, it was short lived but it did drive. So fast forward to yesterday and i go to start it and its backfiring, not holding an idle unless i staid on it. i have double and tripled checked for vacume leaks, checked plugs, went over different parts of my tune and can not figure out what is going on. It will not idle unless i stay on the throttle and if i let off it dies and backfires some. I have attached my tune. i also checked for codes being thrown and there hasnt been any. The cam was installed and degreed correctly so i know thats not it. im at my wits end because im not sure what it is.