Ford Repair: Ford Explorer, luck chris, speed sensor

Question
My speedometer started flickering and then went to 0, the engine sifted from over drive to drive, and would sift back and forth when speedometer would work or quit working, any idea of what could be wrong.

Answer
hey there. try replaceing the transmission speed sensor. without the transmission knowing how fast the b=vehicle is travelling it will have a hard time determining what gear to be in. I think this may have the sensor with the plastic gear on it so make sure that is in good condition as well.
good luck
Chris P