I've read that some newer GTRs are missing springs and can be difficult to set idle. Mine idles at around 1150 - 1200, but if I let it sit and idle half the time it will drop into a low idle (750rpms) and either die or bring itself back to normal idle. Ive noticed the throttle gets a lot of slack and just by touching it I can bring it back. In searching I read that somewhere out there is a thread showing the correct spring config. but couldnt find it.
For all I know it may be something entirely different. Just know Ive had hell trying to set it right.