Mushy brakes 4 life...

Is that would could be causing this extreme interference?
It isn't unusual to have multiple problems. But, it sounds like you are the only one here (and in most of internet space) who doesn't first bench bleed an MC, and all rebuilt ones come w/ such instructions and usually plastic tools to allow that. So, our question is "why not bench bleed it like everyone else and then try again?". You only need to unscrew the 2 tubes and route temp tubes into the reservoir. No need to remove the MC from the car. If you see air bubbles sweeping thru, that suggests that was one of the problems.