Speed Control Slows Down By Itself

Test the vehicle speed sensor/output speed sensor. If sensor fails replace sensor, if it passes perform the following test:
1. Check for transmission DTC.
2. Perform the speed control switch test on the DECEL switch, if it fails replace switch.
3. If the switch passes, conduct the vacuum supply test.
4. If it passes, conduct the servo vacuum test. If it fails replace servo.
5. If continuity, replace the PCM.