Check the Rotors
I would check the rotors again with the car off the ground, to see if there is a high or warped spot on the new rotors as you spin the hub. They can and do warp because of improper metal content, regardless of age. I think if you don't find that to be the problem and the car stops in a straight line, I'd be checking wheel balance as well as slipped steel belts in my tires. They can do that when checking for balance. If the car seems to pull to one side when applying the brakes I'd check the opposite side for air in the braking caliper.