I think I'm just getting used to this. I was answering previous responders and I guess it looked like I was talking to myself. I wasn't

 

What does that TSB have to do with your issue which claims the car will not stop when you're trying to brake (aka like the Lexus problem)? The TSB is for a hard downshift condition which would actually result in the opposite of what you're claiming, i.e. engine braking would occur causing a sudden deceleration during braking.

Something does not add up here...

 

The master cylinder, like all modern master cylinders cannot completely fail so you will always have some degree of braking. A failure of this system is very uncommon and easy to detect. You gotta be on the brake and gas at the same time or your idle is set at 2,000....