Just to keep thread up to date we have found that the car has a late 2014 LFX engine and trans so we are now checking the HPFP to make sure it is the LFX one and not been changed to the LLT and then on the weekend we are going to read in the ECU, TCM & FSCM and actually see how or what they did to get it to work with a 2011 system. It might be a hodge podge of VIN numbers or it could be they swapped all modules in from a 2014 but either way we can turn off flex fuel and see exactly what is going on without guessing.
Ok just to update the thread a bit further we got the ECU, TCM & FSCM read in today and they did not bother to link the ECU to the vehicle they just disabled VATS to get around security and since we only had one key present we left it like that for the time being.
Disabled Flex Fuel and checked everything else and there were no issues other than security and flex fuel.
It went into learning mode when the O2 sensors cut in and started dragging fuel out of the trims and was running around 2% when we were done but still has a little stumble now and again and a very slight misfire only detectable on the misfire graphic on tech2win but was still learning so the car has been taken home for a long drive up the hills to see if the problem was entirely the flex fuel sensor or if it has a mechanical issue.
We will keep you posted.