Rough idle after adding 93 octane gas

Hello, you should try resetting the fuel adaptive learned strategy or Keep Alive memory. I would also do an oil change. I would say since the code showed up right after a refueling then yes it has something to do with the fuel. Higher octane is going to burn hotter as well. But after replacing a sensor, especially an oxygen sensor, the memory should be erased so the ECM can relearn the fuel strategy. Changing the oil will help too. There is always some blow by that gets passed the piston rings, obviously it will be more with an older vehicle just due to age, but the oil gets diluted with these blow by gases and you get a mixture of oil and gas in the crankcase. This is why oil changes are good in general, but it should help.

If there are misfiring cylinders, this can indicate a lean exhaust as well because the oxygen sensor can only read oxygen not fuel. So, during a misfire you get unburned fuel and oxygen going down the exhaust, but the oxygen sensor will only read that oxygen so it can trick the ECM into seeing a lean condition. If there's a rough idle, there's misfiring cylinders. So, getting some regular gas in there and resetting the memory should do the trick. You may want to pull a couple of spark plugs just to see what condition they are in.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers