Took the car for a drive yesterday and noticed as soon as it fired on all four cylinders it started a misfire almost immediately. Alowed the car to warm up and the misfire persisted including a short drive to see if it would clear.
I checked the HT leads nad distirbutor cap which all semed fine and rang Rob at RatRace for advice. I was sceptical when he suggested that plug may have fouled but did as he said and checked them. I was surpised to find 3 of the spark plugs were fouled i.e. wet and sooty.
Changed the spark plugs for an old set (NGK BCP7ES) and the car ran fine! Have ordered a set of BCPR7ES from OPIE Oils for £10.65 delivered.
I expect this is to do with the engine needing to be set up properly by Emerald (Scheduled for 09/04/2018). Clearly the engine is running too rich at idle and has fouled the plugs through frequent (cold) starts and not getting up to temperature; because I am keeping the use to a minimum until the engine is mapped.