Stalls when it wants. 94 grand Cherokee?

got a 94 jeep grand cherrokee with a 4.0. it stalls while driving and starts it self back up from the turning the engine over. it started after a 200 mile trip. seams to be worse with ac or cruise control on i think its related to the heat outside. its been very warm here and it seems the hotter it is the worse it is. my truck is NOT overheating, i had a fuel pressure tester on it when it stalled and it did not go below 30 but im not sure what the pressure should be, it runs fine at 30 and when it stalls the pressure does not drop, i had a problem like this befor but it set a crank sensor code and it was my crank sensor, this time i do not have any codes and i have an old snapon scanner without snap shot so i cant get the data at the stall point, anyone very familiar with jeeps, help would be great.