I have an 05 Silverado 1500 RWD, I have had an issue with my brakes for months now. My brakes tend to drag at least once a day, the pedal is very inconstant as well. It gets stiff and very close to the top of the pedal when I notice the drag. I have found that it is making my truck feel sluggish at times when it is acting up(can feel that the brakes are dragging, slowing the truck down) and then normal other times. I have replaced both calipers, rubber hoses, the MC, the rear drums with the cylinders and all, and after about 4k miles if that, my brake pads are gone on the insides. I have no other idea what to get it fixed, besides maybe replace the booster or the ABS module. Any help would be GREATLY appreciated, thanks.