I have a 383 LT4 with all the toys and I was on the gas the other day and the car backfired, dropped to idle I gave it gas again and ran ok to about 4k then ran like sh-t and died. Discovered the coil was dead. Changed it now I have fire to the plugs again and it won't start. I do have 40lbs of fuel press. Tried starter fluid, changed the icm and still no start. help