Help! 2000 Alero dies while driving

My 2000 Alero turns off while driving (after about 7 to 15 miles) and will not restart for 10 to 20 minutes. I've had people tell me all sorts of things - catalytic converter, fuel pump, cracked head. My serviceman replaced the fuel filter, but that didn't fix it. Parts are really high so I can't afford trial and error. He's having a time diagnosing the problem as the car seems to run well when he drives it short distances. I've read on the net that lots of folks replaced the fuel pump which didn't fix the problem. Fuel pump costs $348.00. Any suggestions? Please Help. It's my only car - single with 3 kids and a job!

please check out my thread.