Update:
Hi everyone, Just wanted to let you know what the deal was with the running rich and missing when trying to lean it out issue.
So, the cars idle is a little bit variable according to the piggy back ECU (could be a bit of electrical noise), car dial is steady.
During Idle it is jumping between 2 zones of the fuel map, when I tried to lean it out I was only leaning one of the two zones and this resulted in a large difference in the amount of fuel in the two zones it was jumping between. The result of this was the a missfire on cylinder 6 due to loss of spark, followed by more cylinders if one of the two zones was leaned out more.
Not sure what the factory ECU was doing to make this miss happen, but when both zones where leaned out at the same time the miss did not occur.
One more step forward.
Cheers
Edward