They have a recall on them. Just go to your nissan dealer and tell them about the recall. Also This may help, try cleaning your throttle bodies,changing spark plugs, Just a basic Tune-up. i had very bad hesitation problems when i first got my Z. It turned out to be the Mass Air Sensor,Engine Temp Sensor, Coolant Temp Sensor. Hope this helps, Later! E-mail me if you have any questions. Shawn