Reported Gas Mileage is Double Actual
 

My father-in-law had a Roush Supercharger installed on his 2008 Mark LT (Lincoln version of the F-150) and the Ford Dealer sent the PCM to Roush to be programmed. The truck runs fine, but ever since the PCM was reprogrammed, the trip computer indicates that he is getting double the gas mileage that he is actually getting, and the range to empty is also double actual. The Ford dealer's only proposed solution was to remove the supercharger, and Roush had no suggested fix. Has anyone else seen this issue? Thanks.