I've become a bit of a believer in the use of Injector Cleaner
So: for your info Supercheap Auto has Vavoline Fuel Injector Cleaner on sale.
Its a twin pack of 2 x 350m bottles for $12.99.
They have others in slightly smaller bottles that work out tobe a lot dearer.
I'm not sure when this special ends.
Regards.