Does this only happen when the engine is cold? When the engine reaches full operating temperature is it ok? If so it sounds like a problem with the automatic choke. Years ago on the older cars (thinking here back to the days of marinas and cortinas etc!) cars had a manual choke and we had to pull the choke out on a cold morning.
These days most cars have automatic chokes plus whats called a 'stepping motor' (not sure if your model has this...ring your local Nissan dealer). A stepping motor raises the idling speed of the engine whilst cold. When the engine becomes warm enough, the stepping motor reduces the engine idling speed back to normal.
Be warned that these inobtrusive looking little black boxes can be expensive. Either ring around vehicle breakers asking if they have one or take your car into a garage and have a manual choke installed, which will bypass the need for a stepping motor.