Hi Scotty, I have a 2010 Hyundai Sonata 3.3 with roughly 80k miles on it. I recently bought it used maybe 6 months ago with all the maintenance records. I replaced the gasket for my cylinder head cover and put some quality rtv on a lip where oil was leaking (i’m talking maybe 1 droplet a week). At this time I also replaced my spark plugs. Anyways, while going up and down hills at ~40-50mph my engine would sometimes stutter, especially when there’s a stop sign on top of a hill. After stopping and then accelerating, my car would jerk forward aggressively. I did some research and figured I would replace the fuel pump because there was one for my car that was about $105 and if that fixed the problem I would be happy. After replacing the fuel pump my car ran better (from what I could tell) for about 3 months before my fuel pump failed. I towed it home and at this point I decided that I had better replace my alternator because I thought that may have been the issue (was planning to anyways at one point because of all the oil stains on it). Anyways, turns out that the fuel pump had failed and I had that replaced for free because 1A auto sent me a new one. I figured I would try it again because I could’ve gotten a defective part. After putting it in the car started as normal and it seemed that my problem was fixed (for now). After this, I also replaced my battery because I have upgraded electronics in the vehicle and the previous owner actually put a smaller battery in than my car was supposed to take (not enough cold cranking amps as it’s getting colder). Anyways, my car drove fine for about a week and a half and here I am today and I’m currently not driving my car because I noticed symptoms like not having enough power in the pedal and strange tachometer movements. For reference, I’ve replaced the 3 front spark plugs, have done a transmission change, done 4 oil changes since getting the car at 66k miles, cleaned the MAF, replaced front gasket, replaced front breaks, changed power steering fluid, replaced alternator, and have replaced the fuel pump. My question is, Do you think it’s just a bad fuel pump and I should replace it with a different brand, my fuel injectors, some other component of the fuel system, or something else? Other useful information includes that the gas tank is very clean from when I looked. Should I get a fuel pressure tester gauge and what do you recommend?

Thanks for reading, Im a 21 y/o college student that likes saving money and most importantly likes to do things the right way (I’ve had experiences where some mechanics have done more harm than good). Obviously trying to fix things blindly isn’t a good practice at all, but I just indulged myself in mechanical work since I got this car (I really like the car)