2006 dt466 egr low power low boost

Sounds to me like a fuel issue. I’d put a clear line on at the head to make sure you’re not getting air into the system. Like Inderjit said 56 PSI is not ideal, usually want it closer to 65 with no drop under load. Change the regulator and if no improvement change the low pressure pump.

 

Did you ever figure this out? i have a truck doing that exact same thing. and we have seemed to do the same by capping off the egr. im hoping to see if you found anything or fixed the truck??