The truck started throwing a lean code. Checked the fuel pressure and it was low so I replaced the filter and got 2# back. Not enough so I put a new fuel pump in her.
Now she's throwing lean codes on both banks. Clear the codes, drive the truck for 20 to 30 minutes and the codes return. Run diagnostics while driving and the short and long trim voltages on both banks look normal.
Mine threw codes saying it was running lean Nd looked all over for a vacuum leak. Someone on here told mme to clean the MAF sensor and that's all it was. They make a spray for cleaning it. Have been told only to use that and not cleaners such as brake cleaner.
Brake cleaner and MAF cleaners work good. Carb cleaner leaves a film. Just spray the filaments, don't touch. Also check the PCV hose elbows front and rear. The rear one tends to get overly soft and cracks.
Sorry for not getting back. The truck's been parked while I worked on other stuff.
Cleaned the MAF sensor, no change. After clearing the codes, the truck runs for about 20 minutes before the Check Engine light comes back on. 20 minutes continuous, two ten-minute trips, with or without complete cooling between trips. 20 minutes.
Both left bank lean and right bank lean are being thrown. Both of the O2 sensor's voltages/patterns look normal and regular on the graph.