Hey guys. My cel came on for bank 2 cat eff. (gutted cats with non-foulers) which has never happened yet. I've had the cats gutted for around 2k miles w/o problems.

When I got the car, it had a minor random stumble at idle, that I thought may be normal, but has apparently gotten worse. I looked at the o2 readings and compared them bank to bank. Seems as though bank 2 is the culprit. Bank 1 only varies < 0.1v where when it stumbles, Bank 2 will swing up to 0.7v. The car is NOT throwing any misfire codes at all. Is there any typical idle/stumble/misfire issues with these things? Also, which side is which bank? TIA,

Adam