brakes dragged and turned the rotor into a orange ember

I have replaced the brakes, caliper, and rotor after the brakes dragged and turned the rotor into a orange ember. So what else should I try. It is the driver's side and this is the second time I have replaced these parts. It is still doing the dragging feel off and on now even after the new parts again. This tells me that I replaced not enough parts. What else would cause this? I did not notice a leak but the brakes did stay weak after they were bled. The stopping time is still very slow.