I usually seed a torrent for months. This is usually more than enough time to get at least a 1:1 ratio on each torrent.

I have noticed recently that peers don't stay connect to me for more than a few seconds at a time now. This is of course is killing my overall ratio. I have a feeling I've been a victim of Comcast's traffic shaping. Is there anyway to test this for sure or a way to get around it?

You can try forced encryption but Comcast has spent a lot of time and money to investigate packet transfer. They are not trying to kill BT traffic, just drastically reduce it during mainstream hours. Read this article and try these remedies:

How To Bypass Comcast’s BitTorrent Throttling | TorrentFreak

Happens to me on some torrents that I've been seeding for a few months. Doesn't happen on others. I doubt it's Comcast since it's only on some (of mine).

Thank you for the fast responses. I am currently checking out that link from Jerry.