Firstly let me say I've no specific experience of your engine but generally your snag is pretty standard stuff. That is, poor fueling under load or ignition breaking down also under load.
You have replaced the ignition components that are most likely to give problems and the fuel system seems healthy except maybe low fuel pressure.
My thougtsh on fuel are: check or replace the fuel filter, check the tank vent and check the fuel pressure. On ignition, rotor arms and condensor quality seem to be very suspect these days so I wold make sure your replacements are kosher.
Lastly I and a few other members of our car club have experienced very similar symptoms on 6 cylinder engines and sorted it by "going electronic" The modern hall effect systems are now very cheap, easy to fit and unobtrusive. CC did a piece on the Autosparks system and recomeded it, mine is a similar system bought on the internet and all I can say is that it transformed the engine perfomance