hummmm . . . did you jack up the front end and spin the wheels to see if there is any brake or bearing drag? If its the same try the same test after the brakes are HOT and Cold also whale the front ends up in the air, tap the pedle to see if the calipers is sticking.
Take a tap measure and accruetly measure and compare the distants between the front of the back tire and the back of the front tire. I would assume they should be the same (be sure tire presure is the same on all four) or no wait measure it from the rim serfice not the tire.
Are you compairing the pull on a perfict road(s)?