Well I'll hunt down a PF09 ..
the plugs are 071c's as Ive been running for years with no probs at all .. leads I got with the WS setup from Stu, so they should be ok...about the earth cables .. I have been thinking abouth that for a while (due to changes in the instrument lights when using indicators, braking and so on...) but until now never got the time to follow up on it...but now the car is in for it's winter sleep so as soon as it's on t´he stands I'll "pull it apart" .. sort of
... and have a look.
I still suspect ECU or chip problems though ... therefor I'll try this ECU change as mentioned earlier.
But yes WS has been working good...only thing is that it will do 1 "misfire" from time to time .. BUT ONLY ONE... very strange ...but apart from this much better that the OE setup absolutely !!
Only one cylinder is it the same one every time? have you done a comp test and a cylinder leakage test? just a thought?
Also if only one cylinder have you tried swapping injectors and see if it moves the problem?