have had a few with ECU problems,i take it after plugging in the select monitor that the boost pressure registered is the same as you are quoting,cat collapse a few times and(i hate to say it) the 2.5 problem ring land,all of the knackered engines have had no power but have driven fine,have you noticed any 'blue puffs' on cold start.The symptoms sound exactly the same as the many 'piston problem' cars we have had and had to rebuild.
Gav