chasing down bubbles, humm, have you tried bleeding the master cylinder independent of the rest of the system? A lot of trouble can be handled by doing what is called a bench bleeding, you basically bleed the master cylinder into itself. It can be done in the Jeep and not on a bench like the name suggest. This sets up the "master of the system" to be working in top form and is a solid base to a properly working system. Not doing such can leave you with a spongy pedal that you try to cure by bleeding and bleeding the system when it is acutally a few bubbles in the master cylinder you need to get cleared. Hope this works, it can save a lot of trouble.