Misfire CEL

[vipercwf]

I got bad gas awhile back and it completly stalled out my car and wouldn't run. They agreed to fix it. Since I got it back it had a check engine light and was misfiring slightly but was told it was probably from still having some water in the tank. I've had really weird symptoms since, the CEL has gone on and off and for awhile it stayed away but has come back permanently it seems. It lightly 'pops'(misfires) in the morning (sound seems to come from back exhaust area) but once it's warm I don't seem to have much trouble for the most part. I did notice other day for first time i was cruising at like 35-40 down the road and had a few consecutive hesitations/light bucking but none since. It def hesitates when its cold but problem mostly goes away once warm it seems. The code i'm getting is P0301, which is a misfire cylinder 1(I've already replace the coil, no luck). I just really feel like this is directly related from the bad gas, but the only thing I could think would be the O2 sensor, although from the code that doesn't seem to make sense. Is it possible that it's still the O2 sensor even though it's saying misfire @ cylinder 1? I just never had any problems until I got the bad gas and the symptoms seem to be similar to posts i've read who were having similar type problems and a replaced O2 fixed it, but the code is throwing me for a loop. If it was a bad O2 is it possible the code wouldn't necessarily reflect that? Just not sure how to approach id drop a fortune at the shop im sure, and an O2 isn't cheap to just replace and try. Any kind of advise is appreciated.