Hello Mr. Kilmer. I have a 2008 Chevy Impala LTZ with the 3.9 V6 at around 104k. Almost a month ago my engine light came on and it threw a PO172 code pending and saved. I've replaced the downflow O2 sensor and MAF sensor assembly and the same code keeps coming back. Along with that my scan data shows 64% alcohol in the system even though I never put ethanol in it. What else should I look for to solve this?