A bad MLP (Manual Lever Position) Sensor will make those trans do some weird things. On that trans I believe it sits right on top of the trans. Looks like a fancy neutral safety switch, which in a way it is. It tells the PCM what gear your selector arm is in. When acting up it can let your computer think you are manually shifting into different gears while you are driving. A good scantool can monitor the output voltage of this sensor while driving. Just one of many possibilities, but I have seen them go bad on those Fords. Best thing unfortunately may be to have a qualified trans technician look at her before serious damage is done.