Sorry for the quietness.
Still no improvement with the starter spray nothing changed so probably the inlet is airtight. Although it need quite some staterspray to notice the engine picking up speed when you blow it in the air box it only responds very little.
I did some other test when in the problem revs I unplugged one plug lead it didn’t influence the poor running. I did one by one and NONE made the engine make run worse which is very strange to me
On the other hand it moves the problem back to an ignition problem and not a mixture problem.
Measured compression: all of it within a tight range and within specs ( forgot the numbers (something 12,3)
@ guy thanks for the suggestion.
Although it seems there is already a replacement fitted ( having a white wire)
Can you explain your symptoms ? Did it also vary when the engine is cold and hot?
With the strange plug lead symptoms I’m thinking towards CPS ( which is the one saying which cylinder should fire)
So ordering one soon.
On the other hand it is strange that NONE changed the poor running.