First, I think you should begin that DSC off test now, before you replace the crank sensor.
I do think I've heard of a few incidents where the car activated the brakes on its own...and there are many incidents of wheel speed sensor failings. Not infrequently, those failing have to do with the connector or wire. There's supposed to be a waterproof gasket in there, but I know they can fall out. But, I'm pretty sure you'd find speed sensor codes. I believe it's a myth, that you can fix speed sensors by cleaning the magnets in the hub, but I have read of a few having success with that.
You recall if your car was pushing over to a particular side when it 'cut out'? That would at least help you figure out which side an issue might be on.
Oh, one other thought about this 'brake activating' thought. The brake feeling you're getting might also be just the effect of the engine stopping, which it sounds like it is...then, because the car is moving and in gear, it 'push starts' itself back to life.
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Mangofy your E46!