Cleaning the MAF is something that likely needs to be done anyway but I doubt it will solve the problem. The error is likely being generated by the O2 sensor at the cat. Either the cat is toasted again and the sensor is right, or the sensor is old and needs to be replaced. Since the sensor is relatively inexpensive I would change it first if you are just tossing money at it. Again, since it hasn't been replaced before and is near its end of life it wouldn't hurt. If the problem clears then all is well for awhile. If not then you need a new cat, but you were guessing that anyway.
Just be aware that at this mileage the vehicle is near its EOL so be careful what you do here. Perhaps a junk yard cat this time. Try to avoid spending much because you aren't going to see the value. At this age, bad things start to happen.
In another thread, some schmuck just bought an old Camry with 166k miles and paid top dollar because it had been cleaned up. With mileage like that the thing becomes a money pit. Good luck with yours though--you have likely driven your money's worth out of it!!
2007 V6 Camry LE, Built TMMK 27 September 06
"People who think they know it all are particularly irritating to those of us who do."
Last edited by gdanaher; 03-24-2011 at 12:53 PM.