It's running g like a dream .
I went on to replace the maf sensor which made no difference at all to be honest and was beginning to worry. Next step was the turbo boost solenoid and have to say as soon as I stripped it down I had a feeling it was the problem. Lots of surface rust on the sensor itself. Cleaned and made it good as possible and ordered a new one. From the moment I refitted the cleaned sensor it has been perfect.
So many options to fix the same fault . Perseverance is the key.
Thanks for the help guys