There isn't just one cause though... The links ygmn provided, just like you probably found with your research, shows several areas to check & eliminate as potential issues. Did you test the MAF sensor readings with a scan tool to see if it is operating as expected? Clean the MAF sensor and throttle body? Check all vacuum lines? Check fuel rail pressure? Check fuel injectors? Let us know which of these you've eliminated as issues, and how you tested them, and we might be able to help you further!
Edit: something like this is where I would start when considering time/money spent to check something off the list of potentialities https://www.youtube.com/watch?v=OwJHw5pcsZQ
edit2: do you have aftermarket cold air intake or other relevant parts?
edit3: keep asking questions and giving info, lets get this fixed man! Good luck
edit4: i swear i'm going to quit... is your fuel consistent? Do you use e85 one fill up and 93 premium the next? Has the problem occurred over multiple tanks of fuel?
edit 5: i lied about quitting... get access to a good scan tool and check the 'Fuel Composition' which shows the level of alcohol(ethanol) in the fuel, i've now read that some flex fuel vehicles (like ours) will read abnormally high ethanol content which throws a rich fueling condition. I think you're looking for a fuel composition somewhere around 9%. Higher numbers (unless you're using e85) is not good. There is a fuel composition reset procedure that should re calibrate this (only if you verify it is the issue), but i think it is only available on a GM Tech2.