I chased a P0171 code for awhile and finally decided that I would refresh most of the fuel system when my 4Runner hit 300k.
I replaced all the vacuum lines first, with silicon ones as recommended by someone here, it didn't fix the problem.
FPR
Newer Charcoal canister (mine had a huge crack)
New O2 and wideband sensors
new injectors and new fuel filter and fuel pump.

Turns out the short rubber fuel line in the tank had a big crack in it and the system would lose pressure after a certain fuel level. Great, problem solved! Nope.
Immediately I started getting a P0172 code and I could smell gas every time I would drive. The truck would drip gas at a stop.

I bought Toyota replacement parts for everything EXCEPT the injectors. Pendejo. I'm guessing one or more of the cheap injectors were stuck open and or not functioning correctly, They were leaking at the fuel rail, the Titanic leaked less than those crappy injectors I bought!

As recommended on here I bought new replacements from motorwestperformance.com and I should have just done that in the first place! One full tank of gas and no leaks and no P0172!

Truck runs great and the fuel system is ready for another 300k!
Lesson learned.

Old injectors are 3 months old, basically fell apart as I was removing them.


New injectors from MotorWestPerformance