Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
Sounds like you have the dreaded SCV (Suction Control Valve) issue.
There has been a revised SCV out for a few years now.
Still available from Holden.
You could also have a failing low pressure fuel pump.
I would run a TECH 2 diagnosis of the vehicle first.
Have you had a diagnostic check done as yet?
I hope my suggestions have been of some assistance to you.