Hey, I am but a LR novice but recently I fixed a very similar problem (symptoms the same) and after 2 days of fault finding it turned out to be a poor earth from the fuel pump to the main harness. I can't believe (well perhaps I can since learning about Lucas "the prince of darkness") that such small under size wires and fittings could be installed in a robust off road vehicle with an electric fuel pump!

FWIW?

Thommo
'95 V8 manual ES Disco