2006 g35x, driving down the road and I lost all engine power. No previous signs or issues. After I drifted to a stop, jumped it and electrical was working, and car would rev in park, but as soon as I put it into drive I'd have no engine power and it wouldn't rev at all. I'm clueless as to what this could be. Only check engine codes are P2a00, P0138. Just hit exactly 140k miles.

 

P0138 bank 1 sensor 2 oxygen sensor (the one in the catalytic converter). This won't cause the car to not function properly though, and is probably being caused by whatever the actual issue is.

P2A00 bank 1 sensor 1 oxygen sensor (air fuel sensor in the headers). This will cause the car to not function properly if it's actually the culprit.

I suggest first checking for a vacuum leak like a hose that popped off or ripped on the intake tract, it would have to be a HUGE leak to completely immobilize the vehicle though, next I suggest using an OBD2 scanner with realtime data so you can see what that O2 sensor is sending back. Likely the O2 sensor had a crapastrophic failure and is dead. Uncommon but it does happen, and with the miles that are on it that's definitely likely.