The cox tech rep just used his Motorola tablet to run Wifi Analyzer app (which I then later got from Cydia on my jailbroken iPad) at my house and showed my wifi signal dipping in strength every 5 seconds consistently. In an ironic twist I had a hunch to set it up on channel 1 18-months ago to avoid interference with neighbors' wifi only for most of them to do the same. After setting to channel 11 which no one was on I saw consistent level with no drops.
That may be your entire problem.
For me it is only part one of my slow Cox speeds; now I just get consistently slow speeds instead of sometimes even SLOWER speeds :-/