Well with the impending requirement to drive the car long distances and during holiday seasons I managed to squeeze my car in to "Hodder Automotive" in Auckland just before Xmas (23rd of December).
They put the car on the diagnostics scanner which read as a misfiring issue.
So they checked the obvious.
The result was :
The spark plugs had had it. The gaps were large, The colouration was off (rusty orange in some cases), One had a crack all the way up the ceramic casing and the type of plugs were not the type recommended for a turbo engine (i.e. cheap plugs). So the plugs were replaced with Platinum type spark plugs
In addition the air filter was full of crap.
I'll be taking the car for a long drives over XMAS so will see how this goes but should hopefully now be resolved.
In fairness I should of managed to at least checked the air filter. My assumptions were that this type of stuff would have been picked up by the previous mechanics when the engine was replaced.