2005 savana utility van

GMC Savana van problem, van wouldn't start after lunch! 2005 GMC Savana van 2500 with 4.8 liter motor VIN # 1GTGG25V451226506 116,000 miles I have a service van with 2 doors in the back and 2 on the side, motor oil and coolant levels are fine and the oil was changed 2 weeks ago. The problem...