Jeep: engine rev out of control, vacuum leak, vacuum line

Question
When I step on the breaks hard the engine revs up very high and I have to shut the engine to get back to normal.

Answer
Leave the Jeep in park and unhook the line going to the brake booster.  Make sure to plug the vacuum line.  Step on the brake hard, if it doesn't act up, replace the brake booster.  The brake booster could have a vacuum leak!  Hope this helps, let me know!