Could be your crank angle sensor. Its connected up with the DFI module, so that could be the problem too, but far more likely to be crank angle sensor.
If an 8cyl is the same as a 6cyl then the DFI module is located underneath the coil packs. You will find a connector plug to the right sie of the coil pack. The connector plug is bolted on with a single bolt in the centre of the plug (not sure what size....6mm or 8mm). All you need to do is undo the connector plug and give it a good clean out. Like i said before RACQ mechanic did this to mine and it started first go....haven't had a problem since and its been about 4 weeks ago now...