I just realised that I never updated this thread. It might prove useful to some.
Well, I bit the bullet after realising that I would never ever have the savvy required to get the issue sorted. A trip to NJS and the problem was revealed.
It was caused by a completely coked up intake manifold. So, the intake manifold was replaced, the cylinder head taken off and given a thorough clean and most importantly the EGR was blanked completely and removed from the ECU.
(I also treated her(and me) to the performance remap as well.)
Anyway, once at operating temperature, all the issues were gone.
The trip back home was a revelation. Seamless power thanks to the remap and the blanked off EGR and a steady idle.
So, if you have a similar problem, get the manifold checked!
As always, thanks to everyone who offered advice and big thanks to Neil and the guys at NJS. You'll be hard pressed to find a better Alfa specialist.
Word of advice, if you do use NJS , see if you can get the little yellow Fiat Panda as a courtesy car. It's a hoot.