I'm going to change my original answer a bit as this was happening to me yesterday (1st day with my new, softer cubes has forced me to change my
riding style a bit). When I was going right - no problem, but when I was going left (I am a righty), I'd occassionally get whipped around to toeside.
I thought it was cool as the board is much more snappy now but some of the power slide initiations were unintended.
To rectify it I needed to be more conscious of the weight I was keeping over my front foot and I had to adjust my bindings to allow more of my toe to
hang over the front of the board to reduce the amount of heelside pressure.
It is symptomatic of being over powered but if you drive the front foot into the wind and relax the backfoot a bit you should be OK - or slide to
toeside, ride as far as you like and then jump back to heelside.
So you may want to try that or tighten your trucks up if you can.
Depower Quiver: 14m Gin Eskimo, 10m Gin Eskimo III, 6m Gin Yeti, 4.5m Gin Yeti (custom bridle and mixer)
Fixed Bridle Quiver: MAC Bego 400, JOJO ET Instinct 2.5 & 5.5, Lil Devil 1.5, Sting 1.2
Rides: Ground Industries