Since I have owned my Z there has been an odd behavior that shows up often.
From a cold start the engine sometimes starts stumbling and cutting out, and eventually it stalls. Load or idle doesn't seem to matter, other than load inducing the stall more quickly. After this stall, if you restart the engine it functions 100% normally. You can turn it off and turn it back on any amount of times, and so long as its not a cold start there will be no problem.
It isn't a fuel PSI issue, the PSI doesn't change at all while this happens. It feels electrical when the engine starts stumbling.
In the documentation that came with the car there was an old thread from these forums that had been printed in its entirety.
Found here.
The symptoms are very similar, but not exactly the same. It finally ended up being the Coil Packs for him. Does that sound correct for my symptoms?