[dpaul]

Just checking on your time line - order of things is important, please verify each line:

-car ran fine for most of a year, no smoke, NO CODES (as suggested by no CEL or actually reading the codes?)

-smoking on WOT noted, CEL NOTED (do smoke and CEL correlate well?), codes for all 4 sensors and misfires on bank 2

-replaced pre-cat sensors (did you do this yourself?), cleared codes, CEL NOTED, still smoke WOT, codes only for post-cat sensors, misfires bank 2

Is this correct?

EDIT: sorry, missed post #8. So smoking closely correlates with CEL caused by sudden death of all 4 sensors and misfire bank 2. Hmm. Would be good to determine if the smoke is from oil or fuel (coolant being unlikely IMO). Has the gas mileage changed? Have you looked at the spark plugs? Oil can kill the sensors and it can kill the cats themselves. I wonder if your cats are degrading, with bank 2 being really trashed.