Having gone through the list as recommended we ended up taking out the carb again. On inspection we noted that the butterfly shaft moves when pushed sideways so we took it off to check about wear. We put on another plastic washer on the drivers side of the carb shaft and engine is now idling well at 900rpm and not hunting or dying on idle. Looks like the shat was leaking air.
Luddite I ve owned my Morgan for two years and it is a 1980 model with 36000 miles with a Webber twin choke carb.
