What should I do if the rear trunk latch on a 1999 Jeep Cherokee Sport will wiggle using the key fob can be unlocked manually and the outside latch moves but I can't get the door itself to budge?

I have the same problem and so far i have only found one solution. Climb in the trunk of the jeep and then remove the handle at the bottom of the trunk door (there will be 2 long bolts) this will release the plastic. Then pop the plastic off the bottom part of the trunk (the plastic will not come off all the way because there are 5 or 6 sheet metal screws holding the trim on around the upper part of the trunk). now get someone to help you, one person (the one with smaller hands) will be inside the car and reach their hand inside the latch housing in the trunk, there will be a threaded rod inside of there and what you need to do is have someone slide it (i dont remember if it is left or right) while the other person works the latch. If you cant get your hands in there (i let my little brother do it) you may find it easiest to use a coat hanger. this should release the trunk and then you should remove the rest of the plastic and tighten up the latch inside the trunk.