2006 pathfinder is slow accelerating after a full stop.

[drudgenator]

Hello everyone. I don't know much about car repairs but i have 2 issues with my 2006 pathfinder. First issue is that when i'm driving and i stop, the car takes like 3 seconds after i press the accelerator to get back to speed. I almost have to press the pedal all the way down to get going, after it gets going, then it's runs normal. this video is the closest that explain my problem https://youtu.be/kf2RKfmVPx0?t=16s it's about 3 minutes long. I don't have a trusted car mechanic and i don't want to spend a lot of money to fix this issue with a car mechanic. if i know for sure that it's the intake manifold gasket i can probably do it myself. I get the exact same code as the video (P0171 system too lean, bank 1). I think i've read that this code could mean many things but i think it's the gasket. Have you encounter this sort of problem before, what was the problem and how did you fix it. Or if anyone can assure me that it sounds like a intake manifold gasket, then i'll go ahead and do it myself.
Btw, any videos on how to change the intake manifold gasket on 2006 pathfinder?
Sorry for the long post and i really appreciate it if someone can help me figure this out.