[e3tom]

ever measured fuel pressure ? checked pressure regulator for the typical leak (membrane cracked) ?

 

[SoNic67]

Still running lean on both banks

On my 2.5L V6 Sonata, there is a fuel pressure regulator mounted at the fuel rail fuel input output.
That regulator is operated by manifold vacuum, and that vacuum connection is via a small, short hose. Well, that aged and got hard, brittle, and didn't seal good enough the vacuum. That lead to fuel pressure issues and codes...
I have replaced with a 6" vacuum hose, from Advance Auto Parts, the guy didn't even charged me for it.

 

[e3tom]

On my 2.5L V6 Sonata, there is a fuel pressure regulator mounted at the fuel rail fuel input.

actually the regulator sits at the output end of the rail dumping excess fuel into the return line back into the tank.

 

[SoNic67]

Yep, my mistake.
Long time ago I actually replaced that input flexible rubber hose because it started leaking gasoline, I should had remembered.
PS: Hyundai dealership didn't have one in stock, but Kia had one that was identical.