Pleased to report that car is now running as normal.
coyoteracer11 - you were on the mark with fuel pressure regulator.
With help from Dave H. (The Polisher) we fin ally tracked down the problem to the fuel pressure regulator which on my EU2 1.8 is a cast aluminium adjustable one. I won't bore you with the details, but the problem was a small split in the diaphragm which was allowing fuel to pass through and via the vacuum pipe was finding it's way into the plenum, which because of the slope of the engine was running towards no. 1 cylinder and flooding it. Hence plugs 1 and 2 were black and sooty indicating a rich mixture.
Clearly the split got much worse in the end allowing lots of fuel to pass through, especially when the fuel rail was pressurised and the engine not running to burn off the excess fuel.
New regulator around £60 , but no longer stocked by Caterham or Redline, although latter will now be obtaining. Managed to get a new diaphragm from Glencoe Ltd for £20 inc. P&P.
Posted this in case it helps others
Paul Richards
Area Representative - L.A.D.S. (Lancashire and District Sevens)
LADS Website
Growing old is compulsory - Growing up is optional
Edited by - Paul Richards on 28 Jul 2010 19:18:02