I have had a slight idle stumble for the last few months.
Read elsewhere the golf tee mod has an effect.
Pulled the plug on the fuse and the sumble at idle is greatly diminished.
This maybe happy coincidence, but though I would see if anyone had or has the same after trying.
Re the defib line, it makes sense, the car is fine (im 6MT) with a brush on the gas pedal. Get the revs to 900 and its good as gold.
I think its something to do with the idle set too low from a laymans POV.