I own an 05 Ford F-150 and the fail safe mode happened to me 2 times. I tried putting only high octane fuel in it, at least 91 octain and has (not) happend since. After all the engine in mine is the 5.4 litre and is considered as a high performance and high output engine. Try and see if it work, if it does please post your results on this Ford Truck Enthusiasts web site for other to learn from. Thanks.
My dad had the same issue on is 04 super crew. We had to have the throttle body replaced. I'm not sure of the MFG date but it was an early production as we had the first lariat supercrew in my hometown