Check the cheap things first:

Fuel Filter needs changed?

Did you notice this after a new tank of fuel? Bad fuel?

If you suspect a the fuel pump is leaking, then set the hand throttle to about 3000 rpm and use a flashlight and see if fuel is leaking, do you smell diesel in the engine bay? Quite often the top seal leaks on the pump, do you notice any wet spots on the pump?

If you don't know, then my suggestion is take it to CVI in Richmond. They know these vehicles like the back of their hand. They will be able to diagnose it and fix it.