Did the new pad on the piston side slip in easily with no rubbing or resistance.?? Some of these new pads need to be dressed out a little,sides sanded down,thick paint removed etc. to work properly. Was it working OK with the old pads before the change.?? Did you remove the piston in the caliper and give the seal groove etc a good cleaning while you were in there.?? If all good down low then you need to check the holes in the master for blockage etc.