This van gave me the runaround.
Dealer did the update and the van behaved itself for three weeks.
The dealer took it back then replaced the IMV valve. Behaved itself for about six weeks this time.
I changed the pressure releif valve on the end of the rail after finding it leaking at idle.
the van stopped three days later.
I recovered it to find no crank signal. Replaced crank sensor. It has been fine since.
I had scoped the crank sensor several times and it was OK.
I think it was the pressure releif valve and the crank sensor was coincidental.
Thanks for all your help.