Can't figuring out what's wrong. Please help.

[Shaun Coon]

you could have a bad jag and are you sure you hooked them up right:/
if they were previously hooked up wrong they will tend to do this

[Brandon_L]

If you stall the van door motor it has a few seconds of pretty much exactly what you described. We had the same problem, check out our arm in this video:

http://www.youtube.com/watch?v=KSUL9_TVooI @ 2:45

[Al Skierkiewicz]

Jaguars do have a failure mode where they work fine in one direction and are intermittant/low power/ or no output in the other direction. Have you tried swapping the Jag?