On occasion the belts on our 2002 XLT V-6 start squeaking badly. Last fall (around 22,000 miles) I took it to the dealer where they replaced the idler pulley and a belt. Problem went away until right before Christmas. By the time I was able to get it back to the dealer the problem went away again. Today I ran it through an automatic car wash w/the undercarriage blast. Now they are squeaking worse than ever. I called the dealer, he claims moisture on the belts and pulleys can cause the belts to slip on on the pulleys as they are turning. If this is the case, I would think this could affect the performance of the engine. He said to bring it in and that the belts may have too much slack in them. Anyone have the same problem? Thanks.