I had mine checked by my father in law, Autozone, and Advance on numerous occasions since it came on.
It was a Lean Bank 2, Lean Bank 4 code.
I replaced spark plugs, wires, coil pack, cleaned the MAF. Asked around for advice on G-E.info and talked to my dealer. Nothing seemed to work. I don't have the money floating around to take it to my dealer and let them spend 2 days and $500 hoping to find the problem and then fix it. I understand what you are saying, this is my baby, but I'm to the point that I'm not going to invest over a $1000 into the truck at this point. I'll get a new ride at that point.