So you are saying that you attained superior fuel mileage by applying moderate throttle input while also maintaining that the engine's revs stay below a count of 5000. Also you noted that when you did go over 5000 rpm your fuel mileage dropped at an increasingly quick rate of change.
I would assume that using more then moderate throttle input would also curtain the fuel mileage gains you were otherwise seeing.
<---takes dagger from back...
On a serious note...
The stock fuel tables would account for that. They get "grossly" rich once you pass 5000rpm.
The
stock SVT PCM is commanding {ideally} 12 AFR at 4k. That drops to 11 AFR by 5k which then drops to 10.5 AFR by 7k.
