2000 Jeep Grand Cherokee replaced all four calipers and brakes and drives perfect for a little while and then calipers start locking down

If youve replaced all those parts start by checking everything is mounted correctly. If it is even a tiny amount out it will cause issues.
Next Re-Bleed the brake system starting with the caliper furthest away from the master cylinder and do the nearest one Last.

it could be,, check the brake line going to the brake and see if it has play ,, also, it could be the caliper isn't flowing , once they get overheated the grease in them ( the slide pins) tend to get stuck ,, pull the caliper apart and clean all the old grease of and re lube them

Good chance of caliper to piston issues like you describe, the pistons must move freely (freely a relative term). Easiest to replace with rebuilt calipers. You need perfect brakes. Consider replacing rubber lines at the same time, pretty easy during caliper job and DO NOT let M/C run low on fluid during this process.

If it is only when your foot is on the brake pedal: A lot of new rotors come with a thin layer of wax on them to prevent rust, and so they must be cleaned before the installation with soap and water, and dried thoroughly
If it is only when you apply/release the brake pedal: You need to apply a small amount of grease to the caliper bolts (not the threaded part but the slide pin that is the long smooth part). There is a specific type of grease for this you can get at your local auto parts store.
If it is all the time: Drive around the block, then remove the front wheels and look for a shiny spot on the inside of the rim, or any other components in the area, sometimes the dust plate between the hub and the caliper gets a little bent when you do a brake job, and will grind on the inside of the rim a little bit.

There are some solutions for this kind of problems:
1. change your brake fluid (BF). This need to done regularly every three yrs. , at hard condition's every two yrs.
2. check the caliper. It's possible that one of the two pistions inside the caliper don't work properly (mud or rust inside)
3. check if the brake bads can slip free over the anchor, if there are some rust on it, remove them and check the surface, if damaged, replace the part.
4. check the caliper slide pins. If the caliper can not slide, it will stay in contact with the brake disk, this will heat up the bad and disk and make a noise.
5. check your brake booster (vacuum test required). If you switch of the engine, listen if your hear some noises (air leak!).
If all that wont work, come back again.

take it to a mechanic....;) I have a 2003 jeep grand cherokee 4 wheel drive V8. there probably is not much difference between year models. frist thing remove the back tire you will see the caliper and rotor. check the rotor if it has deep groves on the front or back you will need to bring it in to have it turned or replaced if it is still smooth it should be ok. remove the caliper by taking the two bolts off the back of the caliper. using a pice of wire hang the caliper so it isn't dangling from the brake line. Now is the time to replace rotor if needed .Get a pair of vice grips crimp off the brake line so any trash in the caliper doesn't get into the brake system (if you let the contaminants get into the brake system it can cause costly repairs to the abs system). open up the bleeder valve most of the time close to where the brake line goes into the caliper and usually has a rubber cap. open bleeder valve, take a c-clamp place on inner brake pad and outside of caliper tighten until caliper is all of the way open close bleeder valve. replace brake pads put caliper back on recommend using lock tight on bolts holding caliper on snug fasteners but do not over tighten, lock tight will keep bolts from backing out. do the other side the same way. pull up emergency brake to and pump brake pedal to adjust brakes. bleed brakes and you are done

Yuo need to set your ABS wheel speed sensors.

Something doesn't sound right, you shouldn't have to remove the brake line to install pads. Did you have to do this on both sides? Do the new pads and the old pads look the same? Did you get the caliper on crooked? Just recheck your work first before replacing more parts. When you install the caliper, You have to hook the pad on one side first before you slide it over the rotor.

New revised calipers. and have the new rotors machined right out of the box before installing

Check rubber brake hose at caliper and replace if defective.