It’s odd that the two banks are the opposite of one another. I think you are correct that Bank 1 is technically staying within a normal range, but it’s still indicating an increasingly lean condition with increasing RPMs, whereas Bank 2 starts in a normal range (just a little rich) and then gets increasingly richer with increasing RPMs. You are looking at the numbers when holding the throttle steady, correct? You need to hold it steady for a good 15 seconds or so and let the numbers kind of come to rest (more or less). When you accelerate, it kicks out of closed loop, then goes back into closed loop when the throttle is held constant.
Assuming the numbers are correct, is there any chance the wires got mixed up on the o2 sensors? I haven’t changed the o2 sensors on mine yet, so I don’t know what chance there is of it happening. I assume you’d have more codes, but it’s just something that occurred to me so thought I’d mention it.
If the o2 sensors are working and the numbers are correct, I’m not sure what‘s going on. Originally I was thinking maybe an injector, but if you are misfiring on all cylinders in the bank randomly, that doesn’t sound like an injector. Could be a problem with spark I guess. Not sure, gonna need to dwell on this one some more. Two people on this forum had a sheared off bolt on the exhaust manifold, but I don’t think that would cause a rich condition (not entirely sure though). That occurs to me because you did have a motor mount problem in the past, and bad motor mounts can sometimes put stress on the exhaust manifolds (as the engine moves around too much).
Could it be that the ECU is toast and it just needs a new one?