I have a 2015 f350 and occasionally the turbo stays at 10 psi while cruising with no load and on flat roads. It seems like if I accelerate to fast getting on interstate highways it seems to stay spooled up. The only thing to take it back to normal is pulling off road and turning engine off for a minute. Normally at cruising speed the boost is only 1 or 2 psi. Anyone else with this problem

 

My 6.4 had that problem and required a new high pressure turbo.

In this case perhaps the vanes are sticking?

 

Are you sure you're not in a REGEN ?

I know when my truck starts a regen the boost rises above normal.... to about the 10psi range at highway speeds, no load, level terrain.

I think it's normal and is to help push the extra fuel through the system.

My MPG also drops considerably during a regen.

Just a thought. May be something totally different. But since you said it'll reset after turning the truck off, makes me think regen. Since regens stop if you turn the truck off. But will restart a while later.

 

Regens will also stop if you put it in park, so an easy way to check would be to put it park, but don't shut it off. If the boost doesn't go down after a couple minutes then I would get it in to the dealer to be checked. Good luck, and welcome to the forum. Visit often, and browse. You will learn a lot!