I'm having some issues with my 2009 Chevy Aveo (~65k miles). About three days ago, I got in my car and pulled out of the driveway and noticed some inconsistency in the acceleration. I tested it a few times by giving a bit more acceleration than I usually do, and noticed that the RPM gauge was kind of shaky (usually would just be a smooth upward acceleration before switching gears, but it would stutter several times before changing gears). Twice now, while driving and giving a bit more acceleration, I've had some misfire issues and had the check engine light come on (and the hold light started flashing the second time).
I pulled the code from the second check engine light, and it was a P0303 - Cylinder 3 Misfire. When I searched for the blinking hold light, the first result I saw was a thread about 2009 Chevy Aveos, and a few posters were talking about having to have their transmission rebuilt...which worries me a bit.
So, with all that in mind, where should I start? My brother said I should just grab a can of fuel additive and see if that works, but I've seen him mess up more cars than fix them (not that it's a bad suggestion). I've also had a few friends say I should start with spark plugs, and cursory research of the code and the symptoms make it seem like it's a good place to start.
If I should start with spark plugs, are there any other related items I should replace? I was thinking about grabbing four of these from AutoZone and then making it over to the space in the next few days: https://is.gd/q3fP27
Also, shout out to @TLAR. Tom was kind enough to help me check my brakes a month ago, and I really appreciated that.