Anyone can correct me here if i'm wrong, but my advice is that if you know the truck is working like this and it acts that way when you drive it, park it until you get it checked. Sounds like a lift pump not feeding your VP and the more you run it without it getting proper fueling and lubrication the more damage your doing to the VP. You may get a way with only a $400 repair bill rahter than a $2000 one.
