take the door panel off and actuate the window up or down. Look at the silver bar which runs the length of the door as you actuate the window (you need to pull off the vapor barrier to see the lift mechanism). While you are there, lube all the rails with lithium grease. Watch to see if that silver bar is moving in towards the door skin and out towards the interior of the car while the window is moving up or down. If so, there is a screw that you can loosen to try to align the bar to a position where the rail and rod don't bind. You will know what I'm talking about when you see the assembly moving.
I did those two things (lube and align) on my windows to fix my problem. My problem was as yours; windows barely move when actuating up or down. Good luck.
2000 Dodge 4X4 - Sanger Puller
2007 3.0 X5