I tried resetting the ECU right before starting this morning. No luck.

I don't think this would prove anything but could you unplug the O2 sensor and start it from cold? It will use default values instead.
 
Reason i don't think it will have any effect is because I don't believe the ecu would use the sensor during cold starts because it has to be warmed up (heated sensor) for accurate readings. 
 
Might be worth a shot and its easy to unplug??? 
 
Edit: I see you have replaced yours Lumix but still might be worth doing if you haven't tried it already.

Mrskylighter
I don't think this would prove anything but could you unplug the O2 sensor and start it from cold? It will use default values instead.
 
Reason i don't think it will have any effect is because I don't believe the ecu would use the sensor during cold starts because it has to be warmed up (heated sensor) for accurate readings. 
 
Might be worth a shot and its easy to unplug??? 
 
Edit: I see you have replaced yours Lumix but still might be worth doing if you haven't tried it already.

Yeah I replaced mine last week. No harm in trying it though. I will do it over the weekend so I'm not rushing in the morning before work.

My 97 Bathurst does the same. On first start it stutters and shudders and it'll normally resolve itself. A tiny bit of throttle gets it going too when it's shuddering. 

So many of us with this start issue.
 

SW20R.
My 97 Bathurst does the same. On first start it stutters and shudders and it'll normally resolve itself. A tiny bit of throttle gets it going too when it's shuddering.

When I give it throttle it wants to stall on me.
 
Can anyone confirm if they believe the car stumbles/stutters worse when fuel is low? I noticed yesterday when the fuel was extremely low the car actually stalled out on first start. Second start it fired up perfect like always. This morning with a full tank it stumbled but only mild in comparison.
 
Not getting enough air flow on first cold start?
Different spark plugs, temp/gap ratings?
Fuel pump?
Poor 98 fuel quality? Octane booster?
Ambient air temp? Ice packs in and over the airbox...

The ecu only starts the fuel pump when you are cranking the motor your fuel pressure in your fuel rail is low as it is leaking back through the return line. So the fuel rail is not up to the required pressure. so replace fuel regulator as this is the return point for your fuel to your tank. That why it start the second the as there is the right PSI in your fuel rail. For example after market ECU will prime your fuel pump 3 -5 seconds be before cranking so your fuel pressure is up to the required PSI. If do not want to replace fuel regulator, then add a prime button to FC output of the ECU, press for 3-5 seconds or you can change it by connecting an out put that is triggered only when start key in on at where ignition lights come on. This will have fuel pump running all the time when ignition lights come on.

grosso
The ecu only starts the fuel pump when you are cranking the motor your fuel pressure in your fuel rail is low as it is leaking back through the return line. So the fuel rail is not up to the required pressure. so replace fuel regulator as this is the return point for your fuel to your tank. That why it start the second the as there is the right PSI in your fuel rail. For example after market ECU will prime your fuel pump 3 -5 seconds be before cranking so your fuel pressure is up to the required PSI. If do not want to replace fuel regulator, then add a prime button to FC output of the ECU, press for 3-5 seconds or you can change it by connecting an out put that is triggered only when start key in on at where ignition lights come on. This will have fuel pump running all the time when ignition lights come on.

Thanks for the insight, 92 Hard Top. I will do some research over the weekend and decide how to proceed.

To test that if I'm right ODB style pin area driver side next to map sensor in engine bay. Connect Port FP to +b with a wire clip before staring your car in the morning this turns on the fuel pump with ing on. Then crank it. Then it should start fine first time.

I actually followed this procedure last week. Page EG-217 of the workshop manual. Jumper +B and FP, turn ignition switch on. I could hear the fuel returning/recirculating, felt the fuel line above the fuel filter. Removed the jumper and started the car and it stumbled. I will do the procedure again tomorrow morning to confirm the result.

I doubt it's a lack of fuel pressure as my other car which only switches the pump on at cranking puts up about 45PSI. in about a quarter of a second and fires up immediately to run at about 1500 RPM cold.
My 1998 Rev 5 Bathurst behaves exactly the same 99 percent of the time. On rare occasions IT WILL START but stumble and run at very low RPM as though the ISCV. or some bloody thing in the ECU. hasn't woken up to set for a cold start. I immediately switch off and restart again and it has always then run at it's normal 1500 RPM cold.