88 Chevy S10 2.5 liter massive back fire & dumping fuel.
 

My 88 S10 2.5 now has an intermittent problem will start up every time sometimes run fine for a while then like a switch it just starts backfiring popping rough idle sometimes it will die sometimes it will not. The backfire was so massive it blew a hole in my muffler. It is dumping way too much fuel through the injector after startup. Had a previous problem of not getting fuel in the injector after startup and have replaced the FP FPR TPS OPS CTS IAC batt alt starter O2 sensor Fuel and air filters fuel injector plugs wires cap rotor ignition module. Checked the map hall effect switch and ECM all checked out good. Have set timing don't know what else to check. Confused of why I now have an opposite problem that I had before. Still resulting in the truck I cannot drive.