Engine race to 2500 on shift from 2 to 1 in 4 who lo.
 

Sometimes when off-roading in 4 wheel low, and shifting from 2 to 1 in manual mode to approach rough area the engine may race to 2500 rpm with no gas pedal. The vehicle speed was low enough to not see engine rpm jump to 2500.
it felt like engine had been powered to 2500.
this for 2011 f150 with 6 speed auto tranny.