CEL on MAF or o2 Sensor?? Please help me:)

[violametallic-S-]

I have a CEL, hooked it up to a scanner and it said "o2 sensor circut, slow response, bank 2 sensor 1"

First question, which one is that?

And second is, i read that it can be the MAF triggering the CEL, how can you test it to know for sure what the problem is?

I cleared the CEL, it came on 2 days later, same diagnosis. and I cleared it again and it hasent come on in about a week, but it sure rides like garbage! power loss for sure and just not smooth at all.

I bought all 4 OEM Bosch sensors and will be replacing them soon, but now im worried if it could be the MAF. I dont want to throw out 400 dollars for the CEL to come one again.

Can someone please give me some advice?

Thanks in advance.