Finding Brake pulsation issue

Warped rotors are a fact. If you have a dial indicator you can check rotor runout, but it is likely you don't have a dial indicator. If the brakes pulsate when applying them the rotors are likely warped. The most common cause of warped rotors is over- torquing the lug nuts. The lug nuts need to be tightened using a torque wrench and not a pneumatic impact wrench. Having the rotors turned (machined) may or may not fix the problem. F-150 rotors are not all that expensive so I would suggest you get new rotors and while it is apart change the brake pads no matter how good they look.

http://www.motorweek.org/features/goss_garage/tire_changing

Probably a front rotor warped. Jack up the front tire off the ground. spin the wheel by hand, if you hear rubbing of the brakes at one spot of rotation, then it is warped. If no sound, remove the tire. Squeeze the pads by hand to make contact with the rotor. If it grabs at a certain point while spinning, it's warped. As bob said, over tight lug nuts will cause them to warp. Especially if the rotors are extremely hot and one runs through a puddle, splashing water on them.