Backfire and battery drain

Https://youtu.be/C1mlJAs7hL4

Video I made that sums up the problem.

After fully charging the battery it runs fine for a bit. Then starts to backfire under load. Runs even worse with lights or AC on.

Battery light is on even though it seems to be getting correct voltage. But voltage drops dramatically when lights are on(electrical load).

No codes.
New alternator.
New battery.
New Distributor.
New ignition coil.
New starter solenoid .
New battery positive cable.
New cable to starter.
Timed it perfect to 10 TDC.
No parasitic drain. Pulled all fuses under driver side panel and checked.
Rough Idle, way smoother when IAC unplugged.

I feel like there is an electrical short that I cannot find, I think once I get the battery light turned off(problem fixed) the car will stop backfiring and all good.

I have checked the grounds and the green wire that goes from the alternator to the ECU. It has continuity and seems to be working from alternator to ECU Pin.