Drum brakes noises

I have the stock drum brakes on my 91 mustang, however I have changed all the springs/hardware, and the shoes, however when coming to a stop, i can hear a clunking noise coming from the rear brakes, which seems to speed up/slow down relative to the wheel speed. Could this be the master cylinder? I can feel it very slightly in the brake pedal too

Yea i replaced the self-adjusters, and the brakes are in spec. Two or three clicks up on the e-brake will hold that car in place usually, and the balance feels pretty good on the brakes front to back (as good as drums are going to feel). Im really baffled by this noise.