My guess is its not the primary o2 sensor. It should throw a specific code for the 02 sensor.
I would try cleaning your MAF sensor first off. Or if the diodes are worn through, then replace it. Try cleaning it with brake clean at first. Also if you notice some wetting on the top of the sensor or if silicone is coming out of the MAF then then its bad.
check your pcv hose. They collapse at times and create vacuumm leaks.