Sounds exactly like your IAC (idle air controller) is so dirty that it's not allowing air into the engine per its job when you're not stepping on the accelerator pedal. Though the thread at http://www.wranglerforum.com/f5/bogg...igh-40235.html
is for the 4.0L engine, it talks about how to clean the IAC with a can of throttle body cleaner. Your 2.5L has a similar IAC but I'm not sure if it's exactly as shown in the illustration in that thread.
This should be about a $6 fix for you.