2002 RAV4 D4D (SWB) loss of power at 3500revs?

[A7DUO]

I have experienced a problem recently in my 2002 SWB D4D RAV the day after a long run down the motorway,

The following morning - initially engine light on and loss of power, then limp mode for a bit. 

After changing the diesel suction control valves and noticed a slight improvement, and the engine light is out.  However, this hasn't fixed the problem as its still flat and hesitates over 3000revs. 

I have tested tested the actuator itself and that is working correctly. So this works but its more the device that the actuator-actuates that is in question now

I can't find any useful reference points to tell if the variable veins in the turbo are working correctly, althogh I will continue looking into that today.

I have not yet replaced the MAF on the air box yet, in case that is playing a part in the problem - but want to dis/prove functionality of the turbo and fuelling areas first. 

Any pointers on these components and tests grately appreciated