Comcast and Bittorrent

I'm a new comcast customer and I've noticed I have a good bit of trouble when I try to use bittorrent. I've noticed that when I start a torrent my upload (on the torrent and otherwise) is capped at about 3kb/s. I can close the torrent and my speed stays like this for about 20 minutes to an hour and then it corrects itself. I've tried using random ports but am having absolutely no luck what so ever. I generally go through port 12008 and use the newest version of utorrent. Am I the only one experiencing such problems?

I'm also a comcast user
and if I let utorrent go use all my bandwidth it can run up to about 2.12mbps (thats right MBps) and upload at about 80kbps
but normally since I like to use the compy while using utorrent I set it to cap at 500kbps and 50kbps (download and upload)
So definitely your ports