I think it might be the rotors and pads but it seems to stop fine, the brake pedal sinks at a stop sometimes so I know the master cylinder is going out but some times stopping at all speeds I hear a pop when I apply the brakes? Low on brake fluid, air in the lines? Maybe even suspension? 1993 f150 4.9

 

Check your radius arm bushings, might as well eyeball the pivot bushings too while you're under there.