Based on the no restart or hard start, I am betting VP as well.

Mine did the same thing when it died, but I was still getting good economy.

Dave

 

im betting on the VP44 as well, talked to my friend from cummins, you symptoms are a classic, but rare case of injection pump failure. According to him, low boost and bad mileage without smoke are tell-tale signs of a VP going bad, especially since you did find out that the lift pump was out. He suggest getting a new one and upgrading your banjo bolts to the newer style as well. Vulcan performance as well as BD power sell these kits. If you have the know how, you can replace the VP yourself if not, your talking 2400 bucks to replace it at the local dealer. He also said that if you can find a cummins service shop near you, to use it cause they are usually cheaper on parts and labor.