Thank you all for your input and ideas, Final analysis: EGR valve had faulty feedback potentiometer causing driveability problems. Intercooler had split(remarkably small hole, about 1mm by 2mm split, but it may have had more than one of course!), in my case it was the bottom that had bulged and so could not be seen without complete removal.Major pain to fit as so much had to be removed. ACR fault code text was incorrect which unfortunately sent me in the wrong direction somewhat. Shaun