From the OP's original post.
I have replaced all the ignition system components (all plug and distributor/coil leads, coil, rotor arm, spark plugs and distributor cap). All filters have been checked and replaced where necessary. The engine is fitted with a Facet electronic fuel pump (pressure tested OK) and Weber carburettor.
There is always the possibility that one or more parts that have been replaced could show similar fault, however, it would be rather a coincidence for the symptoms to remain exactly the same.
