Power delivery issue

DPF clean

Boost pipe not split

Turbo boosting
Full service
Injector cleaner

Fuel system cleaner

Injector seals

Cam gasket

MAP sensor replacement
MAF sensor replacement

Turbo actuator replacement

The OBD reader is not throwing up any faults either. I may have missed a couple of things off, we've checked that damn much!

Basically all the usual culprits have been checked or done and we still can't get to the bottom of it.

The car just seems to lack any power and to get anything out of it, needs to be very high RPM - doesn't like to be under 2k RPM at any speed it seems. The engine does seem to run pretty smoothly, albeit with a little black smoke out of the exhaust still when booted.

Has anyone had a similar problem or have any suggestions as to what we can look at next? Help would be much appreciated, as it'll be broken for parts if I can't resolve it, which would be a real shame!