Does the engine managment light flash when you lift your foot off the gas whist driving :question
No, the engine management light has never been on while driving, but i was wondering as the car was stored for more than four years whether the condensation/damp has allowed diesel bug to form. looking at the pics for stripping the in tank lift pump, its possible that the filter could be blocked with slime type substance and rducing the general flow of fuel to the engine, but this make me wonder if it would generate an EML fault for a fueling issue? :-/
as Kneepad sys its easy to clean the lift pump in the tank.
I'd also drain tank and ditch the old fuel and give it a service (oil change air,oil,fuel filter).
also buy 2 forte fuel diesel treatment and put one direct in the new fuel filter and the other in the tank with about 30l of diesel this will clean out the fuel pump+injectors.
As you said its been sitting for four years run it until the 30l of fuel are almost gone then change the fuel filter even if its only done 130miles just incase any crap from the fuel lines has been moved.
As you stay close to the M-way take it for a good italian tune up. once the engine is hot boot the arse out of it red line it in 2nd(breifly) this helps remove carbon built up
