Hey y'all I'm new to this forum. My mom has an 03 suburban non flex fuel. She's getting the P0171 code. The auto shop she took it to said they clean the injectors and maf sensor but still couldn't figure out the problem. Her engine light is on and at idle her car runs rough. I replaced the maf but nothing changed. then i replaced the intake manifold gasket and immediately after the engine light was gone and the car was running smoothly for 2 days. She was idling at a light for a long time today and the engine light came back on as well as the rough running. I'm lost now, I thought for sure she had a vacuum leak. I checked all the lines prior to replacing the gasket. My next steps would be the o2 sensor on bank 1 side maybe bad injectors or o rings?.. any advice would be great. Thanks guys

 

is it still the same code? do you have access to a scantool?

 

It is still the p0171 code, unfortunately I dont have access to a scan tool.