Cruise Control problems of the 2005 Audi A4

I believe this may be a repeat complaint, but ms. Demeter says it is not on file. 2005 Audi A4 cabriolet, 6 cylinder (normally aspirated). Sudden persistent acceleration. I was rapidly accelerating from about 25 mph going up a hill trying to make a green light about . 2 mile away. When I approached the intersection, I released the pedal but the car kept accelerating. Firm brake pressure slowed the car, but it reaccelerated until I brought it to a stop. I made sure the cruise control was in the "off" position, even though I had not used it. I drove about 2 miles to the next major intersection, where I stopped for alight. While I was sitting there with my foot on the brake, the engine began to rev. I put the vehicle in neutral, and it redlined. I turned the car off, and reached down to see if the floor mat was out of place. I gave it a pull but did not feel it over the gas pedal. I started the car again, and slowly accelerated away form the intersection. The problem has not recurred, even when I tried to reproduce it.