Tech came out the same day i called (pretty awesome). He thought my upstream power was a bit low (37db) so he went outside and fiddled with the cables there. That resulted in my downstream avrg power level going down from 4 to 0.1 (seriously awesome heh) and upstream now around 45.
Didnt seem to fix it so he had me go directly through the modem (dpc3010) which i had done the day before. took a LONG time to get an IP address but then my speeds were as advertised (65down,20up, he was surprised at the speed himself). Which he figured meant it was my router (asus rt16 with tomato).
He then left saying it was up to me to fix it which was fine by me, i know the tech behind the modem well and the guy was really helpful as far as he could help me. So far cox subcontractors sent to my house have been amazing.
tl;dr- After he left i rebooted everything and the speeds stayed good so perhaps it helps to force an IP change if you are having issues