1993 Toyota MR2, non turbo. The powersteering light continues to go on and off

What is your question?

My mom's '93 Mr2 with 52k on it has the powersteering light come on for extended periods of time and then will go off. While this is occurring, the car has no power steering either. What can be causing this problem? Not one service tech can figure this problem out. If it matters, she purchased this car when it was new.