rear brake question for 94 z

[azkkn]

i dont think my rear brakes work, or atleast as well as they should. when i drive down my dirt road and panic stop, only the front ones will "lock up" enough to kick on the abs. if i do the same while turning, it is still only the fronts. the rears dont even leave a mark in the dirt. my ebrake works, sort of. the first time you pull it it goes all the way up, and the second time it goes 3-4 clicks up and holds pretty good. when i am driving it normal, and come to a stop, it squeaks really bad every time i stop, and i feel like i am pushing the pedal more than i should have to. all 4 rotors, and all the pads were replaced about 3k ago, with all new parts. the car sat long enough for the rotors that were on it to rust bad enough to not be useable. when i installed the new parts, the calipers seemed to not be stuck or hung up at all. any way to test the clamping pressure of the rear calipers? or any other suggestions?