RR 3.5Efi Died today - help

The Rangie has just died.First time it's done it. Was coming home, and
it conked out. After much cranking, during which it fires a bit then
dies, it ran. About 30 seconds later it stopped again. Now it cranks,
starts to fire, idles about 200rpm for about 10 seconds then stops
again. Keeping the starter running and it just repeats the process.
Refuses to run up.

Anyone got any ideas?

Alex