I have a 97 Jeep grand Cherokee limited ed 4x4 with a 318 its running better then it has before for about 30 min then after that it starts running pretty badly the rpms are all over the place when you give it any amount of gas but after the motor cools off it runs great again any one have similar issues I've already replaced the Crank and Cam shaft position sensors the cap and rotor new plugs and new coil

Have you ever overheated it real bad, and/or cool it off too fast, and/or just got the truck from someone else. If yes to any of these it could be a warped head.

Advance or Auto Zone will scan for codes free I would try this. Does it overheat or just run bad the problems are different.