i have an 87 z28 with a 305 v8 and a five speed. i am having a terrible problem with extremely rough running and a severe backfiring problem ( bad enough that it has blown apart two mufflers ) i have regrounded the battery, replaced the fuel pump, the ignition module in the distributor, new cap, rotor, plugs, plug wires and all of the sensors ( map, maf, etc ). any ideas ? i forgot to mention there are no error codes being stored and that it will just smooth out and run fine for a while

 

You may be having timeing issues. Have you ever changed the timming chain, It may be wore, cause it to jump time. I'd start there. Goodluck, Charles