Sounds like a similar problem to my VX Berlina (which is why I joined today). Mine is a V8 and has an intermittent issue of sluggishness down low. I pull out of the driveway and its jolting as other members suggested but once I get to a certain speed its fine to the extent I can give it some and it goes like normal. I initially thought it was a missfire but then realised it should affect the whole range not just down low. My check engine light comes on randomly and has since having extractors/high flows etc installed so thought it could be Oxy sensor or coil pack related but never had this issue so I gather it wasn't those.
I have just changed oil, plugs had the injectors professionally cleaned today, new fuel filter done but my wife called saying it's still doing it. Interestingly, I had a new radiator put in not so long ago so maybe I'll check the clips around the engine and check similar to redls1 has done and see if I can see anything. Failing that time for a diagnostic scan. Holden want $150 for it. Does anyone in Sydney (Revesby area) know if anyone else does them for a better price?