You sat for awhile didn't you? (I"d have to go look at the other thread again). If it did sit, a little Sea Foam may not hurt.
If the O2 failed, you'd probably have a CEL. I'd be a little concerned before thrashing if you have a CAT tune loaded but aren't running a CAT. Do you know what tune you have loaded?
What grade fuel are you puttting in? Do you live somewhere where they overload it with ethanol? I think Skip had some trouble with corn additives at the pump.