I do not know the engine, but the low power investigation starts very similar in all engines. Remove the turbo outlet boot and pressurized to 30 lbs, and look for leaks, at the CAC, manifolds, piping, connection, test the waste gate for leakage and full travel, and crankcase pressure. Then isolate the CAC and test it, at 30 lbs pressure it should not loose more than 4 lbs in 15 seconds.
Change the fuel filters and check the pressure, be sure you are getting full throttle, check the air intake and filter, be sure the oil and coolant level and strength are correct. Do a valve set and inspection for broken parts and abnormalities.
From there on you need someone with more experience with that product.

 

First question how do you know the wast gate isint working ? just becuse you hear the turbo means nothing , what you have for boost? shoud be about 25. You say it has rough acceleration is it skiping ? If you have low fuel pressure on this engine it will give you low power and a skip if the pressure is real low, spec is about 75 psi. to check there is a shrater or compucheck fitting on the filter header, also check the rock catcher, its the little cup that is screwed on just behind the fuel filter. Most people who service the truck forget to remove it and clean it. woud help a lot if you have axcess to a scaner or softwear

 

:whs