Truck starts in the morning but won't restart after driving a while

Hello, there are so very many possible causes of trouble with this engine and vehicle that I can't possibly begin to offer any suggestions. Especially at 16 years old and who knows how many miles and previous work performed. And, every single one of these engines by now has had major repairs -- so -- it's downright impossible to give you valid advice. You need a Ford Power Stroke Diesel 6.0L technician specialist. They are out there, and they are really good at troubleshooting these engines. There isn't a single one thing that I'd guess at. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops