Ford Repair: front brakes, ford explorer xls, quality pads

Question
got a 2000 ford explorer xls and got a brake problem that I can't figure out. The problem is that the passenger side pad always wears out long before the driver side. I already changed the calipers (2x and both sides) the 8" or so hoses that feed them, the rotors them selfs, pretty much everything except the master cylinder and the lines that come from it. Anyone got any suggestions on what the problem might be. Also this is only with the front breaks the rear wear out evenly.

Answer
forget the master cylinder thats not it-both inner and outer pads are wearing or just one of them-i would check the slides where pad holder is and caliper mounting for-rust/sticking pins/dirty or bent anti rattle clips. and make sure you are using good quality pads after making sure slides etc. are clean something is holding pad against rotor and if calipers and hoses are ok you have to look in spindle area
(caliper mounting and pad holder) good luck.