[guye]

Now let me preface by saying I'm no expert, and haven't worked on modern motors at all.

However I've managed to get my old '89 Range Rover classic running nicely, and it has a really early ECU setup with basic sensors. (Temp, MAF, throttle position, etc).

I had a problem with similar sounding symptoms to yours that actually turned out to be caused by flooding; there is a thermistor (separate from the temperature sensor) that specifically tells the ECU to run really rich on startup until a minimum effective temperature is reached. On the rangie, these thermistors are known to blow. To test it, I simply removed the lead and checked for resistance of the thermistor using my cheap multimeter. I then placed a suitable resistor (in this case 170ohm) across the lead terminals to trick the ECU. Engine started and once warm ran like a dream.

I haven't learnt the subtleties of modern V8 (yet), but maybe this will give you something else to look at if there is a basically similar setup.