There is 1 TSB for a fuel filler tube, CODE P0442wow thats odd cause my filler neck with bad (rusted through) although ive never heard of anyone else having this issue. Im chasing o2 sensors myself right now.
I think your muffler bearings are worn out.as i was driving today the check came on at a little over 50k miles. is it most likely a sensor or sometthing of that nature? i have true dual straights (no muffler) for a couple thousand miles, but could this be the reason also?