I know nowt about the diesel miggy's but I had a very similar problem with a Ford Granada some years back .. most frustrating it was in and out of garages loads with no fault found.
It eventually died on me on a motorway run, went from gutless after a long steady cruise to dead and would not restart... called out the AA chap, who had a thought and dived into the injection system where there was a small, and not in the Haynes book - or apparently the Ford knowledge base - a small in-line fuel filter, this was partially blocked with what looked like tissue/paper stuff, cleaned it out and all was fixed.
His reasoning was something like this .... under constant throttle setting the fuel flow through the filter is also constant and becomes "smooth", the debris was then "coating" the filter such that it was become blocked so on extra fuel demand none got through, the act of lifting off (and in your case - dipping the clutch) changes the fuel flow, disturbs the debris and fuel then flows again... normal driving constantly changes the fuel flow so the blockage doesn't build up.
My suggestions to you are simple .... check all the filters you can and look out for paper-type contamination.
Probably no where near the mark... but worth a thought ??
