Hello, can't say that this is your problem but I can tell you that last year the exact same thing happened to me. Multiple misfires all in the same bank and front right O2 sensor not working properly.
After a lot of work and trouble shooting finally figured out that it was the ECU sending bad signals to the O2's.

Bought a used ECU for $100.00 and had it programmed to mate with my truck. This was another $100.00...only took about 2 minutes. It has been fine ever since.

I also had replaced the coils packs, wires, plugs and O2's before figuring this out.

 

 

Thanks Disc oh no. Unreal.. As per suggestion, took a vacuum line off the intake plenum sprayed throttle body cleaner in a little at a time bringing the rpm up. watched as little by little the voltage increased on the o2 and low and behold no more misfire hopefully my hair will grow back now lol

 

Cool!
You may have some injector O-rings leaking on those three cylinders. If the problem is a vacuum leak, that's one of the only places it can be leaking and be bank (or single cylinder) specific. You could do the same test but this time spray around the bottom of the injectors on the three misfiring cylinders.

 

Since doing what was suggested the old girl is behaving herself lol. the O2 is cycling correctly etc and no misfire. I did replace all the seals on the injectors while the intake was off but will still spray around them just incase one didn't seal correctly.
Thanks again
H.

 

Wow, that's weird! The oxygen sensor came back to life?!