Internet Connection

First of all, i dont know if this is in the right forum.
i'm just a newb so please cope with me.

Whenever i start a download through from a browser, the internet speed is about 100 kbps, but then starts going down rapidlyto the point where it stops at 60 kbps or 30 kbps or anything around that.

The same thing happens with limewire sometimes

Bitcomet's highest download speed for me was 80 kbps.

I've tried to set my max half open tcp connections to 70 but nothing worked.

Wat can i do?