1999 Power down, gas eating???

My father drives a 1999 Express van. I'm in Canton, OH but he left to work down in New Orleans. When he had left his van had about 184,000 miles on it. It's 1000 miles down there and he is probably averaging about 150mi a day. He has complained that his van doesn't have the balls that it used to and now it eats more gas. What do you guys think could be the problem with a van that has somewhere around 186,000 miles on it?

Assuming you're not kidding here, it could be due to loss of compression do to high mileage or certain ignition components such as wires and plugs or certain fuel system components such as injectors in need of replacement.

Why is it that you think I am kidding? I'll tell my father that he should check those out. But I am being honest here.

Well he changed the plugs, got a new air filter, and ran some 93 in it, and now it is bad to tip top shape.