I had to laugh, sorry but we named our TD4 on a Y plate, The SLUG,...we call him Norman now.
I had a similar problem.Travelling back up the M6 I felt a bit of a chug, as if the fuel was not going through, then it would be ok again.Found it hard to get to 3000 rpm and it felt as flat as a fart.It gradually became worse and over a couple of weeks, black smoke came out of the exhaust when I pressed the accelerator.So armed with the info of various forums, and the Haynes manual my hubby bought me for Xmas, I set too, to see what I could find. What I was looking for was..
1.Holes in rubber pipes
3.Little filter at the back of the engine
Found this.........a split hose, intercooler
to manifold Britpart No PNH000020, we are lucky in having Teesdalelandrover.co.uk just a couple of miles from us, and he had one in stock,........£12.
Fitted the new one and could see the old one was also rubbing on part of the engine, so..........
Made a little collar from the old one to give a little more protect and tiewrapped it on.....
I think there was a small split when we got him, and over a period of time became worse.Thats when black smoke and complete lack of power.
And Welcome .Org.