5.7 hemi rough idle and low backfire out exhaust any ideas

no the plugs look good i guess i should have provided some history when i originally built the car two years ago the motor was a new crate motor and until just a couple months ago the engine ran great no issues then this rough idle thing started and when i ran a scan on the car it showed the o2 sensors were bad i replaced them with sftermarket ones and that seemed to solve the problem but today the idling and popping returned so i changed the sensors with nkg sensors and again the idling was fine and the backfire was gone but i just feel something else is wrong