They are pretty intermittent and always have been. I've never had a shut off problem unless some obvious line was not attached under the hood. I think I need to learn a bit more about where the shut off valve is, I suppose it could be that. My brakes don't feel hard and the shifting isn't harsh.
My kids are particularly embarrassed when I have to pop the hood and hit the stop switch!
BTW, the shut off valve, or what I THINK is the shutoff valve, the white thing under the green check valve, makes a buzzing noise with the vac line connected, so that seems a little suspicious. Attached with large red arrow.