Was your car fully warmed up when you encountered this? The ECU code contains a couple control paths for cold-starts that affect timing differently. There is a fail-safe for when the car is re-started after cold-start before reaching 55c (i.e. it stalls before warming up properly) - this can cause significant jumps in timing between on/off idle resulting in bucking and hesitation at low speeds. This goes away as soon as the coolant temp hits 55c though, and only occurs if you stop and restart the car on warmup before it does hit 55c. As to the exact reasoning behind why those clever engineers at Nissan did this is anyone's guess ;-)
