by resetting your ecm to 62 mph you will actually loose fuel mileage.the best fuel mileage is a truck set wide open and drive slow.If you use the horse power you will loose fuel, but if you have it to use and dont use it then the mileage will go up.
I havent noticed fsc going down,in fact seems to have gone up
Gotta agree with Steve...Guido had his 7.3 ecm flashed....opened it wide up...he has gained almost 2 mpg running at 70 mph...