Holden commodore v6 ve

Without codes there's not much we can do, but those V6s are similar to the ones in the US cars in many ways, even if they have been altered for RWD from FWD as a lot of those V6s are setup for in the US.

First thing I'd do without codes is change the spark plugs, especially if it has over 100k miles - iridium plugs can hit 120k miles in a lot of cases (and they don't degrade as quickly as traditional plugs) but 100k is the upper limit for iridium before you have issues. In Australia, 160,934 miles is when they hit the equivalent of 100k US miles. If that doesn't work, change the coils out - generally speaking when it comes to GM V6s, they're parts bin specials in the US (unlike the V8s here, especially Corvette and Cadillac V8s) so you can pretty much buy them for very little everywhere. It's probably setup for RWD with a drive shaft but it has the same coils as a V6 Impala and many, many others.

If these do not work, check for oil in the pistons - if you see excessive oil in the pistons by the plugs, the piston rings are bad and you'll need to rebuild the lower block. I know you guys have real consumer protection laws where you shouldn't have problems if the vehicle is relatively new so that may be an option as well.