So then I'll start from the first issue and end with today: (on my 1988 300zx base)

First the rear driver side caliper started leaking fluid at an alarming rate, and of course this was the same day my truck went in the shop, so was filling it up daily. Then the pads on that caliper stuck to the rotor and nearly caught it on fire.

I got the gasket for the piston, new pads and rotors and got all that installed then bled the system. That stopped the leak and now everything should be good as new....SHOULD.....

Now here's the problem, the parking brake cable had to be adjusted to move the caliper and replace the gasket and even now as it sits the parking brake cable is as loose as loose gets. I bled the entire system at all 4 calipers, not a bubble in sight. But now the rear wheels are locked up and if they do move the pads make an awful noise on the rotors.

Has anyone else had this problem? or maybe there's something different about these systems I'm missing? any and all advice will be GREATLY APPRECIATED!

crack the bleeders and see if they release. if so something is restricting the reverse flow of fluid. a miss adjusted brake rod on the master could cause this issue. or if you used the good old hold the peddle and open the bleeder until it drops to the floor. you may have killed the master.

if they don't release when you open a bleed screw then the piston is not assembled correctly. did you rebuild both sides? or just one.

Check the cable linkage at the caliper. and if everything there moves freely, just buy new calipers, they are cheap. the winding self adjusting mechanism inside the caliper is likely buggered up and it's gonna be a lot easier to just replace the caliper.