2006 Explorer 4.6 v8 has no power to tow up mountains?

Let it rev.

Overhead cam motors without turbos need to spin to make power, and at the same time, won't be hurt one bit maxed out. Your shift points are set short of the electronic rev limited, which is set well short of any mechanical limits. With better breathing and programming the 4.6L can wind out to 7,000 RPM.