Finally replaced all 4 O2 sensors w/ generics for $160.

[RandallNeighbour]

I know this is going to add insult to injury, but quite often a bad or failing MAF will cause the computer to give O2 sensor fault codes. They have quite a lot to do with one another and play off one another frequently.

If you are sure your sensors are clean (no greasy fingers on the tips before the install) and the wiring is correct, it just might be your MAF. I hope it's not but it just might be.