I put brakes all around on my mystique several months ago, and I had the same problem. I put rotors, pads, rear shoes, rear drums, wheel cylinders, etc. For a few months, and a few thousand miles (can't really remember how long) my brakes were weak. I bled them time and time again, but it didn't help. Then, with time, they got better, and now I've got what I consider to be good brakes. I've got a post on here somewhere talking about that. It would have been maybe 3-6 months ago when I posted. I figured the pads were finally seated, or broken in, or whatever they do.