Recently my car has been idling like crap. Went to change the oil today and after starting her up the idle was not smooth. It sounded so slow and weak. It sure wasn't silky smooth. Today it just popped a code 44 so I'm going to change the o2 sensor first. I already cleaned the IAC and tb. IAC counts are good(29 at park) and tps is good. Could a bad o2 sensor cause uneven idle? Could it cause an off idle stumble too? Don't think the car has vacuum leaks. What else should I check?