Im having the same problem in the 32, from the research ive done it could be a) the AFM(s) if so give them a clean, b) the spark plugs, if so grab some new ones c) coilpacks, silicone them up or replace them or d) 02 sensor, this is a bitch to check but ive decided to bite the bullet and get them replaced for peace of mind. Im installing new plugs and coils today, well let you know how it goes. In the mean time theres a sticky'd 02 sensor section or go here http://www.skylinesaustralia.com/forums/Mi...sensor+problems for the other ideas ( he had a 33 gtst aswell)