2001 ford f-150 tries to pull even when in park

I just bought a 2001 f-150 4.6l automatic 4x4 truck. When driving forward the
truck takes off fine shifts through 1st and 2nd like it should but it never tries to
shift to 3rd or OD. It doesn't slip at all and will even downshift from 2nd to 1st
if i get on it. While driving I noticed that it felt like it was dragging or that a
brake was stuck slightly. I drove it home put it in park and tried to rev the
engine. When I did I noticed that the transmission was still trying to pull even
though the parking pin was set and the wheels was locked. I shut it off and
put the transfer case into neutral. When I tried to restart it the motor will not
budge, it is locked up solid. I know its not the motor because it ran fine, had
good oil pressure and the temperature gauge was below halfway. Anyone
have any ideas because I have never seen one do this.