P0171 code, but tested the fuel pressure and it’s in spec. What other issues?

What is your question?

My truck is having a bank 1 system too lean code, checked the fuel pressure & it’s at 60psi. From what I could tell online, that’s on the high end but still in spec (55 to 60psi). I’ve also read online that it could be the intake manifold gasket leaking. How can I diagnose that issue & fix it? Truck is a 2004 3.5 5cyl with 125,000 miles.

What makes this problem better or worse?

It’s a little shaky at idle, and hesitant during acceleration.

How long has your 2004 Chevrolet Colorado had this problem?

A few weeks