Thanks for the info , I been on a run and found that when I applied power below 3000rpm there seemed to be a delay or juddery pick up for a second , then all seemed fine it was more pronounced in 4th gear ..I tried running her hard at 3.5k rpm and got the engine got nice and hot ..and definitely smelt of hot diesel. i have checked all the joints and fittings from the filter , fuel rail and injectors, and no evidence of leaks
It really could just be a leak. Sometimes you can't easily see them, and the mention of the smell of hot diesel makes it sound more likely.
Have you checked the seals to the injectors with the engine running, or just 'statically'? the rubber seals can also go a bit hard/perished, and they tend to leak a bit then.
Also, the air to and from the intercooler could leak.
Another possibility would be a partly blocked fuel filter, particularly if it hasn't been changed recently (how long, what fuel does it normally run on)?