wont shift out of 2nd gear
 

I have a 1998 Tauras. It won't shift out of 2nd gear, and it is not slipping at all. does anyone know if a new throttle sensor would help?
Also someone told me that there is some kind of module on the side of the transmission that might be causing this problem, but I can't seen to locate it. Any help is greatly appriciated.
Thanks
Ken