Diesel specialist required. Someone with electronic tools.

I take it the fault codes have been read? If not, your mechanic is a waste of space.

Hi madf, Just off the phone to the mechanic....he says that when the car came in the first thing they did was hook-up and check for fault codes. He reports that there were "no error codes at all". I asked if that would be considered unusual given the fact the engine was behaving so badly - if not a code on the injector pump then surely other codes for the injector circuit/timing/etc expected? He was adamant there were no codes. He still has the injectors out so once everything is back and working again tormorrow he will check for any fault codes again. Assuming there really are no fault codes showing what is the next course of action? Thanks!

When you say "lift off at speed" do you mean take foot off the accelerator when the car is at speed? If yes then the roughness does reduce (still that sewing machine sound but not so prominent) - but I guess this is because engine is not revving so much (the problem is v.noticeable when the engine is revving above idle).

Cold and hot starting is fine - always been such a great car on winter mornings.

There is black smoke under acceleration/high load. I notice it quite a bit when I am on motorways at 70mph then accelerate above this - esp if car is loaded with family/weekend gear. But it has done this for 2+ years and doesn't seem any worse. After leaving the car overnight and first start in the morning there is blue and black smoke but this seems to disappear after a minute.

Thanks to all for the advice. After taking the car to my local Ford dealer then to another trusted mechanic the advice was the issue was related to big-end bearings. Based on the value of the car I could not justify the cost to repair. Sold the car this weekend.....will move on with my life with a second-hand Mondeo. Thanks again everyone.