Hurrah - found some torque !
At last I have made some progress and found a performance improvement. For others that might be interested here is my story.
Problem - No torque below 2500rpm, nothing then big pull from 2500rpm. Can not use 5th/6th gears on motorway due to no torque. Car dies on long inclines.
Countermeasures tried :
1. EGR valve cleaned by Alfa dealer - no effect.
2. Boost sensor cleaned by Alfa dealer - no effect.
3. EGR valve isolated using thin plate - no effect.
4. Turbo vane vacuum actuator seems to move when engine starts and also with increasing revs.
5. Suspect split hose from turbo to intercooler (very oil) - no sign of split when removed. Refit - no effect.
6. Air flow meter changed - big improvement.
7. Air filter changed. Old one was quite dirty, especially right side, loads of insects etc - big improvement.
8. ECU reset - if the battery was disconnected for 2 hours does this mean the ecu was reset ??
Items 6 and 7 were changed at same time whilst car was in pieces. Suspect air filter had the biggest impact. Not sure about item 8.
Current condition - car pulls well from low revs in all gears with exception of 5th/6th which still feel slightly flat. Big improvement overall. Very driveable.
Observation - radio did not need code after 2 hours with battery disconnected. Strange.
At last good progress, I will run the car for a week to check the full effect and decide if more work is required.
Thanks to all who gave help.