So got my LT1 in and runs ok, idles fine, drives, shifts great, but every once in a while it back fired through intake. So figured had a valve sticking open, re adjusted the valves, runs better but when its up to operating temps in gear and from an idle in any gear it will pop and sputter and die unless you floor it. Replaced icm still does it, old icm tested bad at local parts store, maybe this new one is junk too? Now i have the crappy 3rd gen elderbrock headers and need to put in a bung on the passanger side yet to be able to run o2 sensors, so currently there is no o2's hooked up, every thing i search under doesnt suggest that it would do this without the o2's but since pcm doesnt use them on a cold engine to start maybe thats my issue, since it runs great cold? 96 OBDII engine with standalone harness and re tuned pcm in a 86 iroc is the set up. Opti is new and tested, next step all new wires, coil and coil wire i guess.