again i recomend checking the airflow meter it basicly sets your air fuel mix if there is dirt in it or its poked then it will give u a crap reading and make your car idle all screwy and shut off some times. im unsure if you have checked your factory induction kit but the foam around it some times degrades and all that stuff goes into you airflow meter and sticks to the wire inside but this is only my suggestion from a mate that use to idolise his gtr b4 he got old. hope you work it out cheerz