Very strange problem for me especially since it’s not my car, belongs to my sister. Only code that was set last month indicated the MAF so I cleaned it and the car ran fine. Started to hesitate up hills (steep uphill driveway) so I replaced the fuel filter yesterday and my sister said it drove just fine uphill. Now it stalls whenever put into drive, no codes set and none pending. It will idle in reverse but not in drive.
I don’t know if there is a hose going from the MAF sensor to the throttle body on the g20. If so check for a split in that hose. The engine rocks rearward when the transmission shifts to drive but forward for reverse. Also check for any wires or cables that might be flexed by the motion of the engine on its mounts. Considering the age and mileage on this car, it might be a good time to check the health of the mounts.