Hesitation while driving

Hello,

My car has been hesitating to drive and reverse. The other day I was driving and it was hesitating and ultimately my check engine light turned on but also it told me my traction control was off. I went to get a diagnostic and they told me it was a misfire in cylinder 3 (P0303). I got my spark plugs changed in my tune up last year; which was one of the first things on the list that could fix it.
I ended up having a friend mechanic look into and they thought that I might have water in my gas tank so we put dry gas in it early this morning. A few hours later I drove and it drove fine but my check engine light was still on so that was concerning. I later drove as well and my car was fine and the check engine light ended up turning off but when I put it into reverse up my driveway, it started hesitating and almost chugging in a way and my service traction light turned on as well. I usually can go up my driveway pretty slow but today it felt like it needed a little more gas. What could be causing it to hesitant/chug when going up my tiny driveway or even on flat road.