[camaro95]

Hi, wondering if anyone has run into this problem - camaro lt1 efi stock eliminator with FAST Gray Box ECM, modified optispark which has just a cam sensor, msd crank trigger, Mallory Hyfire VII. Car was running fine and after a pass when letting off throttle engine backfired a couple times and quit, when trying to restart engine will pop and backfire a few times and attempt to run backwards when letting off the starter. Figured optispark rotor broke so removed and didnt see any problem, replaced cap and rotor with new AC Delco parts, no change. Fuel pressure good, Checked timing with light and is firing #1 cyl at approx 300 degrees on damper. Removed optispark distibutor and double checked rotor pointing (is pointing straight down on #1 TDC), verified tdc mark on damper, checked crank trigger is lined at up magnet when damper is at 50 degrees, crank reference is at 54 degrees (same as always) replaced mallory ignition and coil with known good msd setup, replaced crank trigger, still no change. This car has had this combination for many years without a problem until now. I'm hoping that I am chasing the right problem and that timing shouldnt be firing #1 at 300 degrees. I am just about ready to replace ecm setup because I dont know what else could be causing this. Again the car was running fine, put seven passes on it that day and on the eighth pass just after the finish line when decelerating is when this happened and car hasn't run since. Hoping someone else has an idea of what might be going on