+1 with the others. When I have had a truck with slow power windows, replacing the motor and the window regulator has always solved the problem. It's a little more pricey to do both motor and regulator at once, but they are +/- 30 years old, so replacing both the motor and regulator at once makes sense. If you do either the motor or the regulator and don't solve the problem, you have to do ALL the work again to replace the part you already had removed from the door shell previously, but didn't replace.