My problem was a simple overlooked fact that the battery was on it's way out....putting an unusual load on the electrical system. It affected the coil-pack power, fuel pump flow, and alternator load...it caused detonation, misfiring and a rough idle all at mysterious varying times.
I've got a $38 supercheap battery in until I get a decent one, and it works a treat.
I've spent many hours and amlmost a lot of money trying to find this out, try it out it's worth a go.
Dan