1997 Ford Explorer Transmition problem?

Two types of transmissions exist for this vehicle.

V6(4.0L)=4/5R55E or V8(5.0L)=4R70W

If the vehicle is a V6, these transmissions were notorious for a broken overdrive band. To check this, there are two servos on the side of the case. The front one is the overdrive and the one towards the rear is the intermediate. There are two adjustment screws on the driver's side. Take a 19mm wrench and loosen the locknut on the adjustment screw while holding the screw with a eight point socket. Now try to torque the adjustment screw to 10 ft lbs. If the screw torque cannot be achieved, a broken band is detected. Do this with both band adjustment screws. Proper adjustment is to back off screw 2 full turns after torque is achieved. Make sure that you loosen locknut enough so it does not interfere with torque measurements. Tighten locknut while holding adjustment screw from turning.

If the vehicle is a V8 the most possible causes are a burnt overdrive band or a burnt direct clutch pack.

If the fluid is dark with a burnt smell, you will have to overhaul the transmission, regardless which transmission you have. You can remove the pan while the transmission is still in the vehicle to inspect for clutch/metal material in the pan.

Take it to a auto parts store have them run a scanner