Bilboz Lexus

Purchased a used but near excellent condition 2001 Rx300 in October of 2008. Only problem I can report is a strange habitual failure of the Front Passenger Power Window. I've just replaced the power motor for the third time. The first time was about 6 weeks after purchasing. The second was shortly after that for which the Parts company replaced at no cost. While waiting for the second motor to arrive, I checked the master control switch. This seemed to be defective in reverse mode (going up). I replaced the Master Switch when I installed the second motor. In June of 2009, the window started acting up again, rolling down with no effort but, going up, lagged to a point of stopping halfway up. With a little patience and more time, I was able to coax the window to a closed position. I finally got around to replacing the motor for a third time. Trying to avoid a "fourth" motor, I would like to troubleshoot. Window will go up and down with no labor at this time. There's the ever present problem of the window going up all the way and then coming down halfway. I've tried the suggested route of resetting the computer numerous times, with no success. I have noticed that the motor feels hot to touch after just one use and, it seems it stays hot until I disconnect from the master switch or turn off car for a little while. If the car had other problems, I would consider trading in but, the Lexus runs great otherwise. P.S. All other windows have worked with no problems from both the master switch and their own.