Ahh....the plot thickens. If your TPS (throttle position sensor) is bad, cruise won't work.
TCC is torque converter clutch. Call it overdrive. When you are above 48 mph under light throttle, the TCC should lock up, and your engine rpm'* should drop a few hundred rpm'*. What RPM'* do you run at 55mph? If the TPS is bad, you may not be able to achieve TCC lockup, due to the PCM thinking you're not at a low-throttle position, even though you may actually be.
I'd love to see a scantool on your car. Being a 96, most auto parts stores will scan for free. Check for codes, then look at the TPS voltage. With the engine not running, ignition on, what is the TPS voltage with no throttle? What is it with the throttle against the floor? When you press it gently to the floor, does the voltage rise evenly, with no dead spots or 'jumps'?