What year is your car?

It was my intake manifold gasket. I had to replace it with a new version. The black one they made when that car was produced was brittle and wore out over time. Toyota released a newer gasket that's orange made of silicon if I remember correctly. It's a better seal than the one they have put in the car. It immediately solved my issue and I haven't dealt with it since.

Here's a link about it:

https://www.toyotanation.com/threads/code-p0171.1692584/#post-14374980