Finally found time to work on the problem. Connections on loom end of Crankshaft posn sensor plug did look to be opened up a bit so inserted small screwdiver and bent them back together. Is it possible to extract these pins to retension them properly. Other than that sprayed this and other connectors including three large firewall plugs with contact cleaner. Have had no re-occurance of fault for two days now so fingers crossed it was that plug but is was fairly intermittant before. Thanks again to you all for your help. David