Power steering whine + engine bog

tupera

I have a 1998 Ford Ranger and periodically I will hear I whining noise coming from what I think is the power steering pump. Furthermore, when the whining stops (after about 10 seconds) the engine will bog down and almost stall (lasts for about 5 seconds).

Any ideas? One thought I had was that the relief valve inside the pump is sticking closed which may cause the engine to bog down until it finally opens.