after fighting with this thing my 96 jeep gc 4.0 2 wheel drive, has now developed spongy brakes.... that start firm and after inching along in traffic get softer and softer to the point the pedal touches the floor but stops. i have done the bleeding the brake lines to get air out and checked for leaks... there are none. cant figure it out, especially since no brake work was done.... just changed the crank pos sensor and this.... aggravating but hey.... no big deal.... anything to look at or check before i replace the master cyclinder? brake booster? dont know.

 

Sounds like the master cylinder is leaking internally.

 

^^ what I was thinking ^^

 

so look at replacing master cylinder? is there a rebuild kit or is it easier to just buy new one?

 

new one

 

new one and bench bleed it before you install it. Instructions should
come with it on how.