Trans Help PLEASE

Hi, I have a 1994 Ford Thunderbird 3.8 V6, Auto Trans. While driving at any speed the car keeps changing gears, even if your going 60 MPH in overdrive, it will still go in and out of overdrive. If your going 35 MPH it will go in and out of gears. This occurs on hills on flats and even with the cruise control on. ANY IDEA WHAT'S WRONG?
Thanks
Joe

Are sure its going in and out of gear, or just shifting between gears. If its slipping out of gear entirely it might be just worn out clutches. Sometimes the line pressure isn't enough to hold worn clutches together and they slip. At a stop light it almost feels like you just kicked it up into neutral.

If its going between gears and searching, check everything related to the tranny shifting; TPS, vacuum modulator, vacuum lines, computer, etc. It sounds like one or more of the components responsible for shift points is not sending the right signals.

Thanks for the come back Curtis73, its not slipping, it just keeps changing gears. There's no vacuum lines going to this trans, I think its all electrical.

check tranny fluid, level, color, and check for air bubbles on the dipstick.

does this only happen at those two speeds?

are you sure its not the TCC engaging and releasing?

ANY other problems with the vehicle(i mean anything - rough idle, burned out tail light, ect)

your emission sticker should confirm there are no vaccum lines, also is there a second throttle cable from the throttle body to the trans?(don't confuse with the cruise control, which may also have its own cable)

sierrap615, thanks for getting back to me, the trans fluid seems fine, it changes gears at all speeds, I don`t know what TCC is? No other problems and the only lite thats out is the right side big tail light with the Thunderbird emblem so I unpluged the left side but thats been out long before the trans started acting up. Buy the way do you know how to change and where the bulb is for the big light not the lite on the end, its the bulb that lights up the whole lens?
Thanks
Joe