Im having a problem with my overdrive in my 91 4cyl lx. The problem is i have no overdrive at all. All the other gears shift fine and theres no slipping, but it wont shift into overdrive. Please help, my gas mileage sucks without it and highway driving is nearly impossible.

 

You may have to add some trans fluid.

 

could just have a broken OD band. It's fairly common, as far as Ford trannys go. They're know for having a weak OD band that can break easily.