Engine performance issues with 2009 G37 Sedan
 

I have been experiencing an intermittent issue with engine performance - engine will all of a sudden start misfiring and lose power with inability to run past 25 - 30 mph. If accelerator is pressed in attempt to increase speed, engine vibrates violently. When the engine is turned off and restarted, it runs normally for a period of time of a minimum of a few days - weeks. Dealership performed computer diagnosis and unable to identify any related codes or mechanical problems. They told me to just continue to drive until problem recurs and then bring it back during normal hours without turning off so they could attempt to pull a code without allowing computer to reset. Have been unable to reproduce during normal hours. Told by one dealership technician that it sounds like master air flow sensor. Please help! Thanks!

You should probably move this to the "G37 Sedan" or "Engine, Drivetrain & Forced-Induction" Section, you are more likely to get some help.