During idle is when you will be under high vacuum, if you have a leak, you will see P0171 during this time. Clamp every hose you can get to and like @
guybo said, do a smoke test. For comparison sake, here's my log at idle when I had a vacuum leak and was popping P0171 codes.
http://www.datazap.me/u/birdtrd/log-1497578227?log=0&data=6-10-11-30
LTFT and STFT were pegging and AFR still showed lean.