Well.. with the likelihood of me jinxing it - It is fixed!
7 months, 3 different garages, new coils, spark plugs, injectors, fuel pump, fuel filter, timing chain and various pressure sensors later
It turns out that the issue was with a 'Inlet Manifold Flap Position Sensor' - around £65....
wtf!? i don't even want to add up how much money I've wasted trying to sort this problem.
BUT for now, its back to happy motoring (and back to modding!)