I think i'm having the same as you, I tried Friday for the first time in a while and I was getting really odd variable speeds, but all converging to 0Kb/s
I just got about 10 mins of 1.2Mb/s (I'm on 20Mb VM) then it dropped off to 0, then I've done nothing to assist it and it shot back up. I can't tell whether it's VM or my newsprovider though (Im with Blocknews.net) as I don't know how I could test anything to download over http for example, also I don't know if I've reached that stupid cap yet. I normally always saturate my 20Mb until the cap hits then I get the max I should get under the capping rules.