Ford Taurus Idling problems

I have a Ford Taurus SE MY2002, 71000 miles. About three weeks ago the car started to make a hi pitched squeaking noise and while idling the car started to lose power frequently. After it happened several times while I am at a traffic light or in the traffic, I checked the belts which seemed fine. Then I checked the throttle body, seemed like the noise was comeing from there. I cleaned the butterfly valve inside the throttle body. The porblem went away including the noise. Then the problem came back again and I cleaned the throttle valve again and it worked. But the problem came back again after two days. Can someone please help me how to fix this problem. Thanks in advance for your help.