When i was deciding to engineer and re-licence my 1995 XJ, a big factor in the decision was the brakes. They were hopeless and i was not going to go ahead with the project unless i can get them sorted. I put a brand new booster in... no change and the Jeep would just roll to a stop under hard braking.
I read a few forums and the consensus was EBC Yellowstuff pads. I got some and the difference was amazing. My Jeep would actually lock up again. Worth a try, and these pads in the link are supposed to be even better...
http://www.shop.blackmagicbrakes.com...F-BMBP-477.htm
Cheers,