It works both up and down. But occasionally will stop on the way up. Wait 5 seconds and work again, sometimes slow, sometimes fast.

 

More than likely the motor... one sure-fire way to test, swap it for another switch. (Not sure if the passenger switch will plug in or not, you might have to find someone else with an fbody.

 

poop. I hate changing motors. The f-body window motor is rivited in, right?

 

Right, but it's honestly not that bad. Took me about 45 minutes taking every precaution and following shoebox's guide.

 

He's right. Just drill out the rivets and replace them with short bolts and nuts. Very easy really.

 

x3 on drilling the rivets out. Shoeboxes site has all the info and where to drill.

Millions of posts on here, but this is the best bet... Shoebox Window Fix

 

When my motor died it just got slower and slower, till it would finally stop part way up, then I'd have to wait a few minutes till I could get it to go up the rest. It always went down in one shot tho. Passenger sides going down the same road now Mine was very consistent as it died...yours sounds a little diff. I might try a switch first.