93 Dodge Intrepid wont start

My son has a 93 Dodge Intrepid. We changed the Water Pump and everything was fine for a few weeks. We did not replace the Timing Chain as it looked to be in good shape. Started fine everytime. Then after school the car will turn over but will not start. We tried to jump start it, but this did not help. We let the car sit for a few hours and the car will turn over, but does not start. the next day we had the car towed home. when I came home, we tried to see if the timing chain was broken as this was one of the recommendations that we found here. The chain looked OK. He turned over the engine and it started. WTF!!! He drove the car around the area to see if it would have a problem and it did not. We started it several times after that and all was good. This monring on the way to school it stalled on him. We hear the Fuel pump turn on. Any suggestions?