How did you go with this mate? Did holden come to the party and did replacing the sensor make any difference?
No update on this unfortunately.
The local Holden dealer had an injector clean done on the car despite my better judgement (read, the car to me sounds like its overfuelling, which gunky or blocked injectors won't do, hence I queried how this woudl help). Low and behold, no difference. I asked them to investigate the E-Flex sensor, and they simply plugged it into the OBD-II reader, which is showing 1.2% ethanol registered.
Given I have little confidence in the local Holden dealer, I will start trouble shooting this myself. Next step is to borrow my uncles detailed OBD-II reader and see what the injectors are doing on a bad start vs a normal start, so I can isolate if it is overfuelling, and if so by how much, and work my way back from there.
Anyone else having any more luck on this?