Cruise Control problems of the 2003 Toyota Matrix

My 2003 Toyota Matrix xr sometimes accelerates uncontrollably. Usually when I am cruising at highway speeds, when I let off of the gas pedal, the car's throttle still feels like it's in the open position, causing the car to speed up instead of slowing down. It almost feels like if the cruise control is turned on and the car is trying to maintain speed. My cruise control was turned off during each of these incidents, and there was no indication that they were turned on at the time of the incidents. This problem occurs once every few months and I usually don't pay attention to them. The car will accelerate for a few seconds then eventually the throttle will close and the car will slow down and then I will apply the brakes gently. I have informed my Toyota dealer of this but they usually just brush the complaint off and say they couldn't find any problems. I personally think it's an electronics issue where the cruise control system override the manual system without the input of the driver.

Cruise control on my 2003 Toyota Matrix sometimes disengages while traveling on the freeway. Deceleration is better than acceleration, but it is still unnerving when followed by other cars. Frequency is about once a month, occurs on one trip and happens three or four times. The cruise control disengages even when the light is on. My wife and friends have experienced this in my car, so it is not just me. When I turn my vehicle over to the Toyota people for analysis, they can find nothing wrong. I cannot tell if this is an electrical short in wiring within the steering column or in the electronics.