It's difficult for anyone to gain an understanding of the issue, let alone diagnose the cause, just from a description.
If there is an issue with the engine or tranny performance, i would expect there to be other symptoms; e.g. increased fuel consumption, (post up your's), rough idle, higher than normal running temp, etc. Have you looked under the bonnet at night with the engine running to see if there is a spark either jumping or running along the length of a lead? This would indicate an ill fitting or damaged lead that could result in similar symptoms to those you describe. Can you hear a misfire at the engine or exhaust. Does the car perform better when cold immediately after intitial daily startup? Anything like this should be documented and pointed out to your disinterested dealer.
I know you drove others prior to purchase, but if I were you I would test drive another similar car. Ideally at the same dealership. If it does not perform very similar to yours, then get the workshop supervisor / manager to drive both cars too. If there is a marked difference they would be unlikely to then simply fob you off. If you are not satisfied then burn that dealer and log a call or send an email directly to Holden. Also take it to another dealer. Just tell them it's unresponsive and the tranny doesn't feel right and request a technician drives it with you.
A word of warning - Do not tell them you had the throttle body apart! If this was to fail, e.g. one of the screws came loose and damaged your engine, you'd be on your own. Stuffed motor, no warranty.
I am quite adept at mechanical stuff, having rebuilt numerous engines, manual trannies and diffs etc and there is no way I would risk my Redline's warranty by doing that myself!
Finally at this stage I would not let any repairer near the car, unless they are a Holden dealership. Again, if you are heading down the path of a significant warranty claim (which personally I doubt), then you do not want to give Holden any reason, percieved or actual, to deny the claim due to repairs performed by others.
Find a good dealer amd repectfully demand the car is adequately diagnosed.
