Low idle and runs rough, plenty power, replaced egr,tps,iac fuel pump and filter

It sounds like exhaust backfire and it sounds like lil pops in the cat. Could it be a clogged cat? I drove it today about 100 miles on highway and it runs smooth at 2000 rpms but slight struggle to accelerate. When I slow down off of highway it idles real,low and shut off once on me. It is giving a po300 random misfire code and the code for an o2 censor , could it be the knock sensor throwing the comp? It doesn't give me a code for the knock sensor though.