evilpastaI am experiencing exactly the same problem in Garden City, KS. I just noticed it tonight when I tried to watch Netflix. Speedtest.net is giving me sporadic, inferior results, ranging from 3 down/6 up to .35 down/3 up. I finally reached a tech support specialist who had me ping cox.net. I'm experiencing roughly 1% packet loss. This is the first time I've noticed any sort of trouble with Cox internet in about five months of service.
Any chance you could login to your accont at http://www.cox.com and try the speed test under Internet Tools and see how your results compare?