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?

It may have an issue with the flex fuel system components. Also check for weak fuel pressure and for vacuum leaks using Scotty's cigar trick video on YouTube.