Sounds like it could be the AFM (Air Flow Meter). Cheapest way to test it is to swap it with another one to see if that resolves the issue...
It's easier with a GTR as you can disconnect one or the other and it will run off one AFM and stall if it's running off the faulty one!
Ask someone if you can temporarily swap it with someone else, maybe a mate that has the same car!
Also you could try getting the O2 Sensor checked, guess I should have checked what sorta car you have before posting lol. I just saw the thread and thought i'd have my lil say
Good luck mate..