Backfiring and an o2 sensor question

So a while ago i straight piped my s10, i have the 4.3l and i love the sound, although my neighbors hate it. When i did this i just snipped the o2 sensor and figured it wouldnt matter, but im not sure anymore. I did the exhaust about 2 months ago, recently after a car meet, where i revved the car a bunch, it started backfiring. That was right after a tank of gas so i figured "it must just be bad gas". Got a new tank, put some sea foam in it, and the backfiring didnt stop. Went to a shop after about a week of it and the guy there said it sounds like a bad egr. So i took off the egr and cleaned it, i thought i cleaned it well. Still backfiring issues. Today i put in a new fuel filter and it's the same story, just didn't solve my big issue. Could my past choice of cutting the o2 sensor cause the misfiring and pops? Or is it maybe just i didnt clean the egr well enough, or did i lose vacuum possibly by blowing the intake gasket? It only noticeably backfires when its at low rpm and the pedal is all the way down, and when the car is under load, doesnt do it when i have the car in neutral. Also the motor tries to stall when its in idle and shakes the whole car, it also only does this once the car is warmed up.