Just a FYI: all those throttle body plugs are sealed with a 3 or 4 lip silicone seal inside the plug (ie they're waterproof).
Richy: mate if I had time to rip the scan tool out of my car again (hard wired now) I'd let you use it for as long as needed.
Do the earth thing....... See if it helps.
coil packs don't all fail at once (not a cause of the stall issue)
Idle speed stepper motor rarely fails (if it did it will stop in the fully open position = high 2000 rpm-ish idle)
your tps is within the normal range (from our previous logs)
Map sensor would throw a permanent code.
AFM WILL cause idle issues (usually high-low-high idle speed cycling (hunting)) but that is usually apparent in 99-00 gc8's with their failure mode of a fixed output voltage regardless of actual airflow (they lock to a 30-40% limp mode, also known as boost-boom!! mode for the unwary).
BUT...So will a bad earth as the
ecu tries to respond to fluctuating sensor (map,afm,tps, coolant temp) outputs caused by fluctuating reference voltages due to bad/poor earth return (engine block -> battery)
Also note: the car may feel strong if the afm is sending the mixture lean now (if it's failing) lean = max grunt = boom! be careful!