2000 Chevy Express Hesitates and sputters

Hello,

My 2000 Express Cargo Van (2500) has a problem.(5.7L, 150,000 Miles, recently tuned with fuel filter, plugs, wires, roter, cap. Oil changed every 10,000 with synthetic.) My wife drove the van from central NC to Northern PA. No problems. On her way home (no load) the Van started to hesitate and sputter. She said it was like the fuel filter was clogged (she has experienced this before with my truck.). It kept running rough so she took it to Goodyear Auto service upon recommendation of Sears. Here, the computer indicated it was a crank position sensor. This was replace and she was sent on her way. About two miles later the van continued it's problem as before. Again the computer indicated a different sensor (don't remember which one) and the mechanic stated that they should have caught that before she left and only charged for parts here. She went on her way and had no problems until she arrive in the center of Washington, DC where the van died in the rush hour traffic. She was towed to a nearby Goodyear auto service center where they started the van and let it run for about an hour and a half. No problems identified and she was prepareing the paperwork to leave when one of the mechanics came to the office and said the van died. The mechanics then searched for the problem. I was told they found some wires on the manifold cover that were burnt and they were repaired. The invoce reads "found and repair shorted wires to manifold." She leaves and drives to south central NC with no problems. We think the problem has been fixed (over $500 plus $150 towing plus two nights in motels.). The van sat for about a week and today was driven to western NC with no problems. On the way back the same type problem ocurred again. The van is currently sitting in a parking lot about 2 hours from home. Any suggestions would be most appreciated. Thanks.