I have a 2008 V50 2.0 diesel that has done around 105,000 miles. I have an intermittent problem where the engine turns on but with very low idle and no throttle response. To date the following work has been done to it, first by our local Volvo specialist and more recently by a Volvo dealer: (1) filter changed; (2) excess carbon removed around throttle housing; (3) EGR valve has been replaced. I am told by the Volvo dealer that the diagnostic testing is not showing any codes. Problem still not resolved and it is also throwing out black smoke when it does start responding. Issue tends to resolve itself after a number of attempts are made. I am not at all technically minded and so any suggestions gratefully received.