We had a similar problem in our 2002 Alpine. The middle of the bottom track was bowed up in the middle, between 1/4" and 1/2". This made it impossible to adjust the door so it would not stick. To fix this I used a razor knife and cut out the carpet under the track. I then shimmed up the ends of the track when I reinstalled it, making it level all the way across. Now I can adjust the door so it no longer sticks at all.
Doug & Debbie, Wilsonville Oregon
2002 36 MDDS, 2005 Chev Colorado
Blitz the American Eskimo, Barkley the Mini Aussie