Hesitating and humming

1990 Aerostar, 200,000, 3.0l. My van recently started running rough. By rough I mean I hear clicking sounds, the motor shakes at idle speeds, and it hesitates when I accelerate. Around 50mph it jerks roughly then smooths out at about 55. Now there is a humming noise that comes from the passenger front side of the engine compartment. I just changed the water pump and the humming quieted down but it is still there. I was reading about an idle control sensor. Could that be the problem or do I just need new plugs, wires, distributer cap, and feul filter.