NickT said...
if you are skipping downwind it could be your board or your posture. when riding do you look like a C or a 7? ensure your chest is back as this will get your edge locked in.
Keep your kite low too, this will help you keep your edge.
-Sheet Out
-Kite low
-Edge like a b@stard
If you're still overpowered, a quick "bum dip" or hand drag will slow you down.