my r33 does this as well....
could be driving around, and then at a set of lights just *off*, doesnt sputter just turns off as if someone removed the key..
ive had 2 mechanics look at it, both pointed finger at my turbosmart type2 bov that i put on it... saying vacuum leak
so to prove that theory we hooked it up a smoke machine and no leaks were found... plus the problem was there with the standard bov also.
mechanic #1 - electrical problem most likely and need to go to nissan so they can wack there diagnostic computer on it to see where the issue is... (not many mechanics have these since the units cost $80k - hence why nissan service department you must go)
before i tried nissan, went to another mechanic and it had him scratching head also... he increased the idle a bit, that helped a small bit , so now instead of dieing 8/10 times its 5/10 times...
im considering ringing up nissan tomorrow (brisbane) and asking them about it, and also how i can go about fixing my odometer that just stopped