This is my first post on this forum; my Wife calls me the forum King, so I've been trying to cool it down...I have a Flex 6.2L tow package loaded Yukon Denali that has 1o1K; I live on Long Island (New York- if you don't like the current weather, give it a minute) and got the run around due to the climate. I won't detail the ugly moments, but I'd keep two things in mind;1- fuel conditioner for the ethanol use, and on the second incident in a season with ethanol, I switch to super high test +. My truck sits a lot normally, so I auto-start it at least once a week in milder winter/fall weather and every third day in super cold weather, letting it run and cut itself off. Look up the good and bad things about ethanol and they will explain how water is your issue. If she's runnin' o.k., clear the codes and give her 500 miles and learn to KEEP 1/3 of a tank -stop playing, and enjoy her. I will go no saying she never gave me a lick of trouble!