2011 G37S Convertible.
Drove the car on Friday. It was perfect as it has been for a decade. Zero issues.
Today started it and idled to end of driveway and up road, all fine. Then tried to turn and accelerate and the car stumbled so hard it threw me forward when it lost power. It gains and loses power very quickly, like twice a second.
I went back home and in the driveway held the brake and ran RPM to 3000 and let go. It sat there not moving for a second or two then took off then stumbled again. There was a cloud of smoke behind it as well.

The suddenness makes me think there's something in the gas that's bad, maybe water or something that got into the lines while it sat for a week? Or maybe a mass air sensor decided to stop?
The air filters are fine. Recent oil and filter change. I can find nothing wrong physically.

 

I too recently am experiencing this same dilemma. I recently just cleaned the mass air flow sensor and throttle bodies. Have 3/4ths of fresh 91 octane gas. I'm gonna try an octane booster first, Maybe even run some water remover to the take and see what happens. I'll post my results when I do it!!

 

Dealer has had it three days. Lots of carbon on the throttle bodies and spark plugs. So they cleaned them both thoroughly as well as the fuel rails. It at least runs now, will idle, but when you accelerate from stop it still stumbles for 3-5 seconds then goes.

They've reached out to the Nissan/Infiniti corporate tech help, they're kind of stumped.