2007 Vauxhall Astra delayed response from accelerator

Help,
I have the following problem with my Astra - just done 9000 miles. Have taken it to a Vauxhall dealer, but since no problems showed up on 'Tech 2' they refused to investigate it any further. In fact they were not exactaly helpful. Don't know what to do next. (Had an Astra before 8v version and ran it for 7 years & 106,000 miles with no problems - except the common EGR fault)

Symptoms on 'new' car are as follows:

1) Delayed response from accelerator (both when applying and removing gas)
2) Holding back on acceleration.
3) Hesitation on acceleration (especially at higher speeds).
3) Delayed response when easing off on acceleration. I.e. Take foot off gas, depress clutch – revs do not immediately reduce – increases for approximately second (or slightly less) before falling off;
4) High fuel consumption.
5) The problem appears worse when the lights are on (E.g. headlights, sidelights).
6) Juddering when starting off at low/medium revs. Need high revs;
7) Faults more apparent if
a) Starting off uphill when the engine is warm.
b) Slowing down whilst travelling uphill as if coming to a stop (but not stopping), then select first gear to pull away (as if coming to a give way junction) and attempt to continue. The car will judder since although the accelerator is depressed, the engine will still be idling.
c) Accelerating at speed (E.g. on the motorway); depress the accelerator, the speed will actually reduce briefly before accelerating.

After a period of non use then the car drives OK. Problems appear to start after acceleration has been applied a few times. Generally however, the engine must be warm or hot for the faults to become apparent; when cold and first started up then drives perfectly.

Any help, or suggestions of where I could take it (or how to get Vauxhall to investigae further) and at least get the fault identified would be helpful (Gtr Manchester area). I suspect an injector or stepper motor fault.