Ok so i have a 99 ej6 sedan. I swapped a jdm b20b (non vtec). Long story short i put the swap (originally did it in a 98 ej6) everthing went fine and how i planned. Ran fine. Got it tuned on chrome bone stock only modification it had was a h22 throttle body. Bone stock other then that with a 2.5 exhaust manga flow tip. Got into a car accident motor was still intact and no damaged. So i got the 99 and swapped it over and made the certain conversions as needed. Ecu is a p28 with a jumper harness. My issue now is that as i was driving the car on my break from work it was driving normal doing about 30 mph. Came to a slight hill and as i switched lanes and gave it some gas the car bogged down wanting to kinda die out. So i pull over check my wiring harness made sure everything was fine so i drove it back to work with the car wanting to bog out after 2.5k rpm. I got to work turned the car off then back on and its been back firing ever since. When i turn the car on it starts pretty fine. But it’s constantly backfiring and when i rev it she sputters and wont pass 3k half throttle full throttle she completely boggs and holds back. I hear backfiring out the exhaust and a pop/back fire out the intake manifold. Was told it can possibly be a bent valve but im really not sure. Firing order is spot on. New plugs wires cap and rotor. Fresh oil change. Any help is appreciated. Thanks in advance. Also new to the forums.