Got an 87 notchback with the 4 cylinder, 3 speed automatic trans. I'm have a huge problem when I'm on the highway. If I'm going 60-70 on the highway, the trans will shift down to second, back to third, but sometimes stays in second, resulting in drinking all my gas due to the high RPM. It does it even when I use the cruise control. I already replaced the throttle position sensor and changed the fluid and filter but it still is shifting erratically. Please help! I'm not sure what it can be!

Welcome to the forum Jay!

At that speed, it's more likely that you are switching in and out of the overdrive.....There is a switch on the transmission called the TCC. It may be faulty. You should disconnect it and drive around to see if the switching stops. You may get lucky and find a bad connection or broken wire.

http://www.kichline.com/chuck/fiero/TCC.htm

[This message has been edited by Gall757 (edited 01-15-2015).]

Forgive my ignorance, but where, roughly, is the TCC located?

Click on the link and the article will explian..

oops, sorry about that. I read the response too quick and didn't notice the link. Thanks so much!