For the past week I've been experiencing some pretty consistent packet loss, and a lot of high ping/jitter which then leads to a complete disconnect for 10min or more. I replaced the modem with a new one, and the issue has not been resolved. Here is a pingtest I just did: http://www.pingtest.net/result/68097072.png
I'm using a Motorola SB5101U. and here is the information from my modem's signal page if that is useful to anyone: http://i.imgur.com/fuOx9.jpg
I also have the modem paired with a Linksys E2500 router, but the issues did not resolve by directly connecting to the modem so I don't think the router is an issue.
Also, here is a screenshot of me pinging google.com 50 times while having some issues (right after posting this actually). I marked the high pings for easier viewing. Usually I'm getting a lot of packet loss, followed by a disconnect, but that is not present in the pingtest i posted in the original post, or here while pinging google.
Your downstream signal level is pretty low, but not that bad. Typically that modem would operate just fine at those levels, but the levels could easily be fluctuating enough to knock you off line. Most likely you have a wiring problem between the tap and your modem.