Don`t you just love these 16V...(not)....some days I want to sell mine and buy a Toyota.
You need to go through the factory cd`s fuel injection testing section for the 16V. You might have a sensor that is shorting out when it gets to operating temps.
You can unplug the O2 sensor and drive it without it to see what it does when it is not in the loop. But I wouldn`t leave it unhooked for weeks.