Very poor brakes on my CJ7

chech the rod lenth by the pedal this somtimes can be ajusted

try adj the e break cable,it will give u better rear breaks,also have a friend pump up breaks,u look under neath it to see if u see a break line leak,if so,u will see break fluid come out of line,they metal lines and a pinhole will rust in it,also check the rear break cylenders if bad u will see fluid on inside of tires.

sounds like a leak to me too is the pedal nice and firm? why did you bleed so many times just be be sure or because over time they needed to be bled again did you bench bleed the master cylinder before installation? double check that the port on the booster that allows atmospheric pressure in isn't plugged what elevation are you at 15" of vacuum is pretty low (won't fix the brakes but indicates an issue)

I had the same problem with my 83 cj 8. Finally discoverd that the lines were reversed at the master cylinder. switched them and problem solved