Jeep Repair: 98 Jeep 2 Wheel Drive - something is draining the battery, jeep grand cherokee, car wont start

Question
I have a 98 Jeep Grand Cherokee (2Wheel Drive) and it has about 140k miles.  When it runs, it runs great – I have never had any problems with this car.  However, something is now draining the battery and I have had it to the station to be fixed so many times that they can't find anything else to check.  What happens is everything is fine if the car is driven everyday.  But if it sits for more than a day the battery will drain and the car won’t start.  There is no consistency to the problem, it can sit for 2 days and a brand new battery will be dead or sometimes it can take 3 weeks driving the car occasionally for the battery to drain.  Mainly it happens if the car sits for more than 2-3 days, but then other times it has sat for a few weeks and was fine.  This is not my primary car so it's hard to drive it everyday to ensure this doesn't keep happening.  The station put it on the computer and can't find anything on the diagnostic check, we disabled the alarm, stereo since we put in a different one from the factory, replaced the starter, they can't find a short in the wires, yet something is not right.  Would you have any ideas by chance?  I would like to sell this car since I have a new one, but in good faith I can't sell knowing that it has this problem especially since I live in a small town :)  Thanks in advance for any suggestions that you might have.

Answer
there is no advice that can be given but a good electrical tech could find it like myself. It just takes time for the drain to present it self and then braking down the ckts to see what is the cause.I live in the Atlanta area I would be glad to look at it for u.