A3 3.2 rough idle, no CEL, not coils

[Neggert]

I have a 2006 A3 3.2 VR6, 95K I have recently developed a crappy idle. All stock except resonator delete. It sputters and bucks and misfires intermittently. No CEL over the two tanks of gas it has happened. It wont do it all the time. It can be worse at start-up but still does it fully warmed up. it clears up right after getting on the gas and only does it noticeably at idle. I have already completed the following work but it has not changed or helped.:

Fuel injector cleaner
new ignition coils
Cleaned throttle body (looked pretty dirty)

The car was a very clean one owner with seemingly meticulous maintenance. ANY THOUGHTS?

[CLEANA3]

No codes. Do you have a vag

[Neggert]

No

[Neggert]

Anyone?

[Neggert]

Trouble codes just popped up, read from Autozone.: P2099 post cat fuel trim rich bank2
P0174 Fuel system too lean cylinder bank 2
P0040 sensor signal swapped bank1/ bank2 sensor 1

[tcardio]

time for some new 02 sensors

[Neggert]

Changed the pre-cat 02 sensor. Been a week and runs well. No more issues for now. Of note The Bank One and bank two censor have slightly different connectors. I ordered a walker brand O2 sensor that did not specify which bank. It actually only fit the One side. However I slightly trimmed the connector with a knife and the connector fit.