Yeszerd

Not sure if this will help, but do you have access to a scan tool that can read all the modules on the car? a while back I was having a electrical issue on my car that would throw the car into limp mode. Mind you it did have one code I could read, which was a p0600. My basic scan tool wasn't able to retrieve the more sophisticated codes or data that a more expensive one could. Finally took the car to a local shop that had a more competent scan tool and showed a communication issue with my one my modules, swapped it out and been ace since.

I've removed the dash and it's honestly not as bad as a I thought it would be. Certainly not as bad as a dash removal I did on a 90s impreza in the past. It is easy to snap some clips and stuff if not gentle in some areas/ Check this video out, I was able to get my dash out way quicker than expected.

I've had popping issues in the past from having one bad plug where the ground electrode got damaged and messed up the gap, as well as not placing the coil pack connectors in the correct arrangement. These were from my early wrx days.

Did you already try reaching out to cobb for a refund? I bought mine back in nov. of last year and hit them up and should be getting my refund here soon whenever my shipment gets to them.