Slowly making progress... had the injectors serviced which included honing the nozzle assembly and resetting the pop pressure. I also played with the pump timing as it was running still a bit 'rich' and at times like a miss-fire. Moved the pump to a more retarded position and it made it worse, so moved again to a more advanced position (above that of the original setting) and now it runs like a sewing machine.
However, I now noticed that the water pump bearing is starting to make a noise, so looks like ill be needed to replace that at some stage.

