Scenic 1.9Dti Start Problems, ECU/Glow light flashes

[nshand]

I have a 1999 Scenic 1.9Dti.
An intermittent problem over the last 15 months, On trying to start after the Glowplug heat/ECU light goes out it then starts to flash.
The manual says take it to a dealer (3 times and they've had it for weeks, checked diagnostics/wiring etc etc...) In this mode it doesnt start.

No problem is shown on the diagnostic computer.
The problem occasionally occurs after wet weather driving/winter etc. and when starting (the next day) the problem starts.. It can clear after 5 or 20 minutes or 2 days (hence this posting).

More evidence is:
1) Sometimes the engine will start(easily), run for 2 seconds then die with the dreaded light flashing...

2) Sometimes (more often now after 15 months with this problem) the glow/ECU light flashes on idle but goes out just above idle (dont stall the car dear!!). after a while the problem seems to sort itself.

3) My wife says rocking the car (side to side as violently as she can!!) clears the problem. I had a mobile electrician in attendance and this was the cure infront of him!!

4) Wet weather / damp seems to provoke the problem

New Fuel filter, Main Battery, Key battery, ECU checks out ok.Wiring checked ok (Toomeys Laindon), Silicone water repellant spray is used extensively under the hood..

Its a problem thats starting to cause me a major headache... A bottle of champagne to anyone who can precisely identify the problem (hope this doesnt break any rules on here..).

neil.shand@ugs.com