could be a few things one front tire has more toe than the other allowing it to drag one tire at low speed but at higher speeds pulling it left, the shocks could be set up different from left to right i.e. two different spring rates or mounted at different angles, and camber of the rear tires you could have one side getting more traction than the other.
there is probably more i'm not thinking of right now but can you adjust it out with trim?
can you tell if its torq steer or Actually coming from the front end?