I'm looking at getting an '01 with a NV4500 and only 74k on the clock. The guy works for an electric company and hardly drives it since he uses his work truck for most of his transportation. I noticed the truck has a little rough idle to it, almost like a studder. I didn't notice it when the motor was cold. I figure it just needs to be driven hard for a little bit to blow out any possible junk in the fuel. Any ideas/suggestions?

Get a fuel pressure gauge and check the pressure at the injector pump via the schrader valve,