Car has an intermittent problem and will stall and both high and low speeds, or when idling. when this happens and power assist fails, it's almost impossible to steer or to brake posing a serious risk to safety. this first starting happening about once a week last november, and now it's pretty often. stopped driving the car, except to test drive as we're trying to find the source of the problem. we think it's either the fuel or vacuum system and are continuing to narrow down the problem. i am not sure if braking will work at all when it fails, as fortunately it hasn't stalled going downhill. i put all my strength into both braking and steering (i'm a pretty strong woman) to get it to safety. it may simply be stopping due to inertia.