Why do the revs not drop during gear changes on my 2000, vectra x20xev?

Vectra SRi 2.0 x20xev 2000 "W"

This happens anywhere above 2000rpm and 30 mph warm or cold.

When the clutch is dipped, whilst changing gear, The revs will remain between 2-3,000rpm depending where they were before dipping the clutch, sometimes they can rise.
You can then coast to a junction with it revving its ** off and when stopped at a junction can take up to nearly 20secs or so to return to proper idle.

Please note this does not happen if the clutch is depressed under 30mph or below 2,000rpm.

There is no engine management light present, I have changed every god-damn sensor on the engine, Throttle body, iacv, tps, intake air temp sensor, maf, cam, crank knock and even the ecu, the inlet manifold has also been changed along with injectors and pressure reg i am at my wits end, i have searched through all the related vauxhall forums and can find no answer.

Has anybody else had this trouble with their vectra and if so how did you sort it

Many Thanks