dying download speeds

When I go to play a Utube or netflix video the stream starts off fine, then after 30 seconds or so starts to slooowww down and stops. The same happens when I try to download a file starts off at over 100kbps and after 30 seconds has eventually dropped to 5-10 kbps.

I speed tested at 950 kbps
zapped pram
repaired permissions
ran deep clean with 'ice-clean'
reloaded flash player

any suggestions would be helpful,
thanks,
sky

If you tested your connection and it was OK, then it's likely the sites that you're downloading from that's causing the slowdown. I've had the same thing happen to me on certain sites and I have a very fast FIOS connection.
Not much you can do about it.