Do you have any logs? Have you tried working with your tuner to see if they have any input?
Is this something that started happening recently? Or has it been going on since the car got tuned? Has anything been changed on the car recently?
The lean code is definitely concerning and will give you and idea as to what could be the problem. You may have a pre-turbo intake leak. Your front O2 could be worn/failed. Your MAF could be worn/failed. Your MAF scaling and/or injector scaling in your tune could need some work. Those are all just guesses though.
- Chris