Not going in gear on 2004 Ford Freestar

I was driving my ford freestar when suddnely it acted as if it was stuck in neutral and slowed down and would no longer go into the drive or any other gear. What could cause a car of this type not go into gear so suddenly. No fluids are leaking and the transmission and all other fluids are full

1 answer
speed idol control sensor goes bad causeing transmission to not shift properly so alot of people change transmissions when the dont need to..