i'll rule out the caliper, although it could happen, its very rare for our cars, i'll tell you the 3 most common problems when this happens, the first one is the inner bushings on your upper control arm on the side its pulling toward, easiest way to see if it is this, jack up the car, remove the tire, unblot the upper ball joint from the spindle, grab the upper control arm and try to move it back and fourth, not up and down, if it has any play, replace it, the second thing it could be is bad strut rod bushings on that side of the car, way too common failure on these cars, the 3rd is tie rods, again, jack up the front end and grab the wheel and try to wiggle left and right, any play, find out which tie rods are bad and change them, doing all 4 really isnt that expensive, might as well do them all!