Engine sputtering and struggling to accelerate, feels like it's backfiring

Engine sputtering and struggling to accelerate, engine would increase in rpm's but if feels like it's backfiring. It does not trigger any engine codes. I've replaced the spark plugs, checked the coils by purchasing a new coil and trying it on each of the cylinders without making any difference. I've cleaned the valves on the intake side. I have soaked them for several days in engine and part cleaner as I cycled the engine, it seems that it took a lot off carbon buildup but the problem still persists. I found no evidence of coolant leaks inside of the cylinders, neither on the spark plugs or the coolant level. I've used some fuel injector cleaner and drove it for about 60-70 miles without an effect. I've also used Seafoam GDI valve cleaner. Im suspecting either a bad injector(s) or carbon buildup on exhaust valves or burned valves or maybe a clogged exhaust system. Please let me know if you have any ideas or suggestions or similar experiences with these or what I can do next? Thanks