I have a 03 G35, it has been a great car till lately. The service engine light came on as I was taking it to get state inspection sticker. Great timing huh. They would not inspect it due to the light on. The dealer told me the throttle body was setting a code off and needed to be replaced so I took it home and bought a throttle body, put it on, did the relearn procedure, the car runs fine, drove the car tonight for 80 miles but the service engine light will not go off. Any ideas? The car ran fine before I replaced the throttle body. I am starting to wonder if they misdiagnosed the service engine code or something.

The dealer is pretty solid at doing that, check with an independent auto parts store to get the code # and see if you can fix the issue.

It could be your PCV valve. Have an auto parts store check the code for free.