Well for starters, I have a 92 4.3L MFI, and it started stuttering about a week ago, I thought the cat was clogged , pulled that and now do not have one at all. Found a plug wire burned up and replaced with new ones, and new cap and rotary button. back fire through exhaust on exceleration, and idles rough and runs like it has no *****. Here is the upgrades, Magnaflow exhaust system and no cat, MSD Coil, K&N oil and air filter, and E3 plugs. I need help.

 

Did you check the timing?