Missing under load (TD5)

I love my disco but it now starting to try me ! since November new starter solenoid contracts, new psitons in rear brake calipers, MOT time needed new front shocks,ARB bushes and steering box.
It has now started missing under load at approx 2500 rpm, anyone have any ideas ?
I do have a small leak of diesel from the connector at the back of the block would this cause it ?
Local indy reckons that just changing the gasket won't sort it that you have to change the lot do they warp ?
Also reckons the missing could be down to the fuel pump ?

Have you searched for other articles related to this?

Oil in wiring loom, Injector washers, diesel leak-off pipes, Air inlet pipes etc etc ... lots of things can make any motor misfire, and just 'cos there's a weep doesn't necessarily mean the heads fecked ..

Paul D has pretty much covered it....

Assuming it has had a good service (including fuel and air filters) then I would check...

Oil in injector loom.
Fuel regulator on head.
Fuel pump in tank.

Cheers Gents,
the fuel connector on the head is leaking and will get looked at first,evrything fine until 2500 rpm which may be enough vacumn to suck air in ?
We shall see