Ok, so to start this long post, let me say I’m new member here, any advice would be greatly appreciated cause I’ve been pulling my hair out over a week on the same problem over this damn car. I cannot afford a different car, cannot afford to take it to a shop, so I need to fix it. I have a 07 Cobalt 2.2l LS sedan and it had a LOT of issues, I took pretty much everything out all the way down to the head gasket, cleaned everything up, put new head gasket, all new coolant system (radiator, fan, all hoses, ECT, therm, water pump, all seals/gaskets replaced). On the head I replaced ALL the valves and keepers, reused the springs & retainers, rockers, lifters, replaced all the valve seals, lapped the valves, threw that together, put the head on, put new head bolts in. Then started the timing, whole new set (chains, sprockets, guides, bolts) everything lined up, tried to turn the engine by hand and it went around once and stopped. No movement. So I took it apart, had to buy another tensioner since they are one use now, and redid the timing. All marks lined up again, this time I turned the engine by hand and it went around multiple times so I figured good to go. Threw the new timing gasket and new cover/oil pump on, put new harmonic balancer & bolt and new tensioner, bolt & belt on, put new valve cover gasket & bolt grommets in new valve cover and put it on, wiped crud off outside of injectors with a shop towel and put them in, put new PCV hose on intake and slid intake on, put new OSS, MAF, MAP, and KNOCK sensors, reconnected battery and tried to start. Stalled for a couple seconds, then fired up loud like a 90s truck. Super loud and rough startup, and then in 5-10 seconds goes all the way down to normal revs, maybe a little under (500-600) then when I go to accelerate it stumbles as I accelerate, it will get to the speed eventually but won’t really go over 2500-3000 RPM the entire time unless I floor it but when I floor it something sounds like it’s gonna blow up. I’d really appreciate any advice, I don’t mind doing the work and don’t have the money for a shop anyways, I just need direction on where to look/what to do. Thanks in advance for all help and thanks for letting me join!