I'll list all the parts I installed to clear the codes.
1. Driver side exhaust manifold & 02 sensor.
I had a big crack right next to the 02 sensor. I thought that might be a code issue.
I bought a replacement exhaust manifold broke one stud on removal. I removed power steering brackets and resivor so I could get a right angle drill I centre punched the stud drilled about 1\4" into it took a torque bit tapped it in came right out. I also replaced all the studs.
Didn't fix my codes next up new plugs and wires didn't help. I went looking for fuel pressure tester went to rent one took it home no good. The 4.2 l engine doesn't have a Schrader valve. U have to use a special part to tap into the fuel rail. Found one on Amazon $60.00. I was getting 5 pounds of presdure.
I got a new fuel pump and fuel filter installed those pressure came up to specs. Still have codes.
next up fuel pressure rail temperture sensor and injectors.
As I was removing the upper intake one of my heater hose snapped right at the connector. Easy fix. Installed everything fired up no gas leaks or water leaks. But most of all NO MORE CODES!!! I haven't heard that truck run so smooth since I bought it in 2007. Don't give up it can be FIXED.