I have a 92 legend sedan that after driving for a while the pedal will become really stiff and the brakes will start dragging and adding resistance. It doesn't always happen but most the time it does. One day when I got to work it was so bad that smoke was coming off the front tires. I've recently found that once the pedal gets stiff if I force it all the way down then it goes back to normal and the brakes stop dragging for a bit. It doesn't seem to be leaking fluid anywhere , it's got new fluid, rotors, pads, and I replaced a rear caliper. I did a few tests for the brake booster and think that it's fine. Does this sound like a master cylinder, bad front calipers, or brake hoses? I'm not sure how to test to find out the issue. Any advice greatly appreciated so I don't have to throw parts at it.