Alot of times that has to do with the inside front & back channels. Not the tracks themselves but the bottoms of the window frame (kindof a rubber fuzz lined gasket).
If the window isnt where it wants to be it slows considerably. Never had a motor that got weak, mine were good or bad.
Drive for a couple of days without the door panel cause as SOON as you button it up things start going bad again.
96BBB 28K 3.42 Bolt-ons
95BBB 100K 3.73 383 New DD...already
fixt the 4L60E twice
95 Black WB4 Hole...ee...grail
96 Black WB4 No holes in this
95BBB 189K 3.08 Old DD