OK, pulsation is casuse by distortion in ther brake rotors. This is usually caused by them getting very hot from hard use and the cooled rapidly, usually by hitting a water puddle or sometimes the the cool air will be enough. As the rotors get thinner from being resurfaced during a brake job, they get even more succeptable to the problem. It can slso just be age and rust buildup on the rotors.
For this reason, I recommend replacement rather than resurfacing. This will repair the problem more permanently although abuse of the brakes can bring it back.
Be sure to replace the brake pads with any rotor repairs.