See this link for the fault code sequence and resseting procedure.
http://forums.nicoclub.com/zerothread/182298
Is your car modified if so what is done?
Failing that there is no gear indicators on this car and your Z could be running on limp mode Which by doing the fault code sequence I hope you get something to appear failing that It could be A trip to the Nissan Dealership mate.
i.e
Does the car have a CAI (cold air induction kit) or a D1 spec throttle controller.
It seems the throttle could be fine but you are not gaining the right mixture of air and fuel.