I too am having the same problem. My car is an R33 S2 GTST Automatic. It has been stalling while idling at the lights and in some cases takes a while to start after stalling. I have also noticed revs dropping significantly while driving and the accellerator feeling sticky when this happens. Stalled as i was taking off from the lights last night.
Car has been with the mechanics twice who have still not figured out the problem. First time in, they changed the oxy sensor which made no difference at all, 2nd time in they found a fault with the wiring harness for the air flow meter and fixed. Car ran beautifully after this for 3 to 4 hours before stalling again in idle and then 30 mins later, stalling on take off from the lights as mentioned.
My mate was with me and thinks but is not sure that it could be the crank angle sensor and from reading topic "Sticky: Missfire Boost.." it seems other people have had this problem and was solved by changing the crank angle sensor.
My advice, if it's only just started to happen, get it looked at quickly because it gets worse quick.