I just bought this truck a little over a month ago it had a code for a bad injector on cylinder 2 which was dumping raw fuel into that cylinder which would to flood to the exhaust and cause flames, I replaced it and it was still having its issues so I ordered an ecm for it (which a mechanic I took it too told me was bad) Fast forward to a month later got the ecm put it in the codes gone and truck runs amazing when cold once it warms up the truck idles funny sitting and when driving it’s backfiring and has very little power. I’ve gone to the back end of the truck and looked into the muffler when this is happening (half my muffler has rusted off at the end so it starts at the fat part of the muffler just after the catalytic converters) and when I look into it I can see on the left side it’s glowing orange/red. When it’s not acting up it’s not glowing. Could this be a bad or clogged cat? What could be causing this issue if not the cat?