Is it turbo lag?
 

I am new to diesels and turbos. I have an 02 cummins HO I find that when I'm in 5th and 6th gear if rpms stay steady around 1400 or so when I get into the throttle no response at all. Shouldn't there be enough power to spool up the turbo? I do have the p0216 code could lack of fuel be causing this? The truck never smokes no matter how much throttle I give it.

is the truck stock? stock turbo? you shouldnt have much lag with the stock turbo, what if you get the rpms up a little does it spool then?

The p0216 is the vp death code. So it's most likely your pump isn't responding like it needs to

A new vp44 and air dog are going in next week. everything on the truck is stock except for a straight pipe exhaust that was on it when I bought it. It will spool back up if I get the rpms up but it won't do that without downshifting or taking it out of gear and putting it back.