Maintenance & Repair: ford mondeo turbo diesel engine problems

I'm hoping that someone will recognise the symptoms I'm trying
to describe (not particularly easy in itself) and be able to offer
a cause and possible soultions. I have a mondeo turbo diesel on an
s plate, 90k miles on the clock and the car starts easily from cold.
Within the last few weeks, whenever I have had to change from a higher
gear to a lower one, i.e. 3rd to 2nd, 2nd to 1st, the motion of the
vehicle becomes very jerky. The vehicle seems to be lacking "power"
almost as if it is suffering fuel starvation. After a second or two
everything returns to normal.

Within the last day or 2, I have also found that the car seems to be
holding back when trying to accelerate in the lower gears. Its beginning
to drive me mad. Has anybody experienced these symptoms on their cars before.
If so, would you please share the cause and solution to the problem.

The vehicle is regularly serviced by myself. I look forward to reading
your replies.

Thanks for the link Jim. I'll post a message there too.

It's really annoying me at the moment.