1999 Ford Windstar, 110,000 miles, 3.8L

The window motor on the passenger side works and will lift and lower the window. However, it stops working. It will work again if I remove the motor and reinstall it (again, it will stop working after a few hours). Neither the driver's or passenger's switch will raise or lower the window when it stops working. I have also replaced the fuse.

When it does work, the window seems to lift and lower with ease.

Thank you,
Chris