Looking at the previous post we found that the signal going into the modem may have been too high. You unplugged the amp and it got better around 6/21/14 then there was no further response. When did it start again? Or did it never stop?
Also, you said the speed was good, but it was still "dropping". Could you give more data on that aspect? Are you seeing this drop while playing a game? Watching a movie? Browser the internet? Is your wireless dropping? Etc Maybe post the logs, specifically those entries around the time you have the issues. Also, the next time you seem to be having problems try;
Windows + R > CMD > Tracert.cox.net or see here for more info.