Duramax Second Generation: 2004.5-2005 (LLY)
I have had intermittent issues with my Maf sensor for some time, only in higher elevations and just replaced it.
After replacement took a test drive, and noticed a decrease is mpg.
My truck is chipped with duramileage and get about 24 to 27 mpg unloaded highway miles for years. After replacing...