Codes P0171 and P0441

Trying to help out a friend. I have a Tundra also.
But his is a 2000 RC V6 about 104K miles.

Runs great but engine light is on and shows these codes.

He has had work done on it by a friend who is a ford master mechanic but they cant solve this problem.

When they try something the light will go off for a couple days then back on.

So far have replaced the vapor canister, fuel pump, and checked vacuum hoses.

Anyone have any suggestions

Thanks

 

Forgot to list that. The gas cap was also replaced.

 

But did he go w/OEM (or Bosch) for the O2 sensors? If not, many have reported issues with non-OEM coil packs and O2 sensors.

And just checking, if OEM, sidn't install V8 O2 on the V6? Aren't they different?

 

Was the solenoid replaced with the evap cannister?

 

Not sure on that part, but will put it on the list to be sure.

Appreciate all suggestions that keep coming.

The plan is for me to get a list from this forum. And just start replacing parts anyone suggest until the problem is solved. Like me. He likes the truck so much. That whatever it takes he is wiling to try.
So far will try

Another gas cap in case slight chance got a bad one. Cheap enough
O2 sensors.
solenoid for the evap cannister

 

Since lean condition(P0171 Bank 1) can be typical of unmetered air, suggest double checking all vacuum lines(hissing sound), PCV(which is on bank 1 side) including it's hose and clean MAF sensor w/CRC MAF cleaner.
Might also ask friend if he has habit of over filling fuel tank which can be related to P0441.