The dreaded E320 misfire

[growlygrowler]

RBYCC, thanks for the advice. I will order new coils and leads, they look still to be original at the moment.

As a couple of others have said: check on the health of that plug that was cacked up after a while. If it's black soot then it points to a dead or poor spark. If it's oily then you could have more serious problems like a dead valve or piston problems. Do you have facilities to compression test the engine? This may give more clues if it oils up again. Remember to compression test when the engine is up to running temperature