1989 gmc k1500 5.7L engine still misses replaced fuel filter rotor button and cap plugs wires egr solenoid oxygen sensor Fuel pump egr valve replaced two years ago Code 44 still shows so whats wrong?

I'm going to type straight from the Hayes Manual I have about Code 44. "Check the wiring and connectors from the oxygen sensor to the ECM. Check the ECM ground terminal. Check the fuel pressure. Replace the oxygen sensor." It's a code for a lean exhaust, meaning more air and less fuel. Check your wiring, it's old. And go over it good. I missed shorts in wiring harness and had to go over it all a second time. Check the ECM. Do you have accessories wired in to things right? It will make the computer crazy if things are pulling power from a source that's not right.