Thanks for the input zeroboot, but this is a different 'kind' of surging.. Its not tranny based, that I am certain of.
The reason I say this is because you have described it as 'jerky shifting'. Mine, and I'm quite sure its o.l.t's symptoms also, has nothing to do with the shifts (up or down), it simply lurches forward whilst in the same gear if you have your foot at a constant on the gas pedal. Always from cold. There is no lunge or surge, or even any clunks (the clunks when down-shifting could be your rear subframe bushes) when up/down shifting.
Which, while I write this has made me think it may have something to do with the ETC or at least along those lines. Seeing as this is drive by wire, I'm wondering if there is something defective within the ETC system that is making the 'surging' on-off-on-off effect whilst the accelerator pedal is placed at a certain point.
Someone could ask the question 'why does it happen only when cold, why doesn't it happen any other time?' Maybe because when the motor is cold, things are more 'sensitive' and any small differences are simply exaggerated and so translated into this surging/lunging feeling...?
Could there be something in what I am saying or am I talking bollocks?