motor off good brake pressure, motor on bad brake pressure

My experience is that if you hear a noise like what you described then the brake vacuum booster is leaking vacuum and as a result you won’t have good breaking when driving. A leaking brake master will let the peddle slowly go to the floor when pressure is held to the pedal like sitting at a stop sign. Did your wife press the pedal with force to the floor when you bleed each caliper? If not you may still have air in the system?

With the motor off is the pedal firm or if pressure constantly applied does it still move down over time? If it moves you still have air in the system. To help remove it is recommended to bench bleed a new master cylinder before installation.

Normally the pedal remains stiff when a booster failed or isn't working as it's not amplifying the pedal action, so sounds like the booster is functioning.

The M/C to booster rod is a predetermined setting, you should check that it is correct with the new master & booster. Clearance between the push rod end and the seat in the master cylinder should be 0.035-0.045".

For the pedal to booster side you can hold the pedal up against the stop and adjust the rod such that the pin holes line up without pushing in on the booster.

Joules, Lousbby,  Thanks for your reply. I did not bench bleed the master cylinder. To be honest I do not know how to.  I will check again if all air is out of my system.