Originally Posted by willwren
I don't think it has anything to do with you putting it in gear or putting the brake on.
Um, well, that'* a pretty weird symptom all right, but if you can do that repeatedly (i.e. have it all running as described, then slowly press in the brake) and it kills the engine, then that brake pedal is doing _something_.
By any chance do you have an old security system or remote starter, something with a kill switch on it that could be triggered when a Bad Guy steps on the brake? Otherwise, maybe some sort of massive short through the Park release solenoid that lets you shift into Drive after you apply the brake...? (okay, maybe that'* a stretch...)