FIXED
Turned out to be a partial break in one of the ECU wires near the multiplug.
Should of been easy to find you may say, the little fecker appears to have been temperature sensitive and old showed its face when either the exhaust made it warm or the poor connection made it warm, expanded and broke the circuit only to cooled then down and make the circuit once more.
At least I now know all my spares work fine.
Happy days
Well apart form the van which dropped a valve on the way home and is now scrap.