[joec500]

Doubt it's the o2. On a cold start, the engine runs on an open loop and the precat o2's are cold so the engine runs rich on startup for a minute or so. Also if it were a heater circuit failure, generally the car with throw that specific code. Most likely an injector in that bank. Did you swap coil packs from bank 1 and bank 2 to see if the misfire moves? If you find that it is an o2 sensor, precat, I just returned a new one to the pepboys on industrial near fftec. It's the same bosch one as oem. So they will have it in stock. Good luck and us know the update.