I realize this question is roughly 7 years old now, but for anybody with a VG33E combing through this thread after experiencing similar issues - start by making sure there are no vacuum leaks, then you'll most likely need to move on to the TPS (throttle position sensor). If the rough idle is intermittent or only after high idle from a cold start, chances are you need to adjust the TPS or replace & adjust TPS. Here is a good instructional I found while trying to remedy my intermittent rough idle...
https://troubleshootmyvehicle.com/nissan/3.3L/how-to-test-the-idle-switch-1