hi. i gotta problem with my jeep. it kinda died on way home and my mechanic friend thought it was the fuel on/off valve but after connecting to the diagnostics it says there are no problems !!

it starts up - ticks over nicely and runs fine. turn it off and go back to it 2-3 hrs later and try again and it revs its conkers off getting ready to explode !! and as im standing 5 foot away its not me.

anyone have any ideas ? im off on holiday soon so i gotta get it working its a '99 2.5TD ... uk spec

cheers