If the wheel pulls to any one direction harder then chances are you have a siezed caliper on the out front brakes. The other common cause is badalignment, however with it happening while slowing/stopping iit's most likely brakes.
Replace brake rotors and pads. Then be sure wheels are properly TORQUED! Dont recommend machining rotors, not that expensive for new.
Machining just shaves off metal that aids in heat despersion. Maybe turn them one time!