Do you have a digital or analog speedo?
Anyway, I have attached a small file that is the .jpg from a Repair Manual CD I have. It is for my '98, but I think it applies to your model year.
It shows how to check the VSS (vehicle Speed Sensor). Althoughy I do not think it is your problem, it would be wise to test it. The following is the description for the VSS - Speedo operation:
"The vehicle speed sensor (VSS) (Figure 45) is a variable reluctance or Hall-effect sensor that generates a waveform with a frequency that is proportional to the speed of the vehicle. If the vehicle is moving at a relatively low velocity, the sensor produces a signal with a low frequency. As the vehicle velocity increases, the sensor generates a signal with a higher frequency. The PCM uses the frequency signal generated by the VSS (and other inputs) to control such parameters as fuel injection, ignition control, transmission/transaxle shift scheduling and torque converter clutch scheduling."
You can see that if the VSS is not working right, other things would be wrong as well.
Let me know what you find, but I do not think me CD will have your model year speedo on it.
You can get the Repair CD's off of Ebay.
Good Luck!!!