Cruise Control problems of the 2009 Mazda RX8

I was driving on the hwy, the cruise control was on, I had been using it for about 20 miles, occasionally bumping the speed up or down as conditions permitted. My primary reason for that is on long trips I get better gas mileage that way. The divided highway came to an end and there was a traffic light about a half mile ahead, so I bumped it down about 2 mph, then bumped it down a few seconds later another 2 or 3 mph. The light turned red then, so I stepped on the brakes (doing about 65 at this point). The engine reved up, the cruise control did not disengage so I stepped on the clutch. The engine continued to rev up so I pressed the cancel button on the steering wheel. The engine continued to rev up (about 6k now) so I took the car out of gear and turned the cruise contol off. The engine continued to rev up (about 7k now) and I'm completely stopped at the light. No throttle control at all. I shut the car off at that point. When the light turned green the car started fine and ran normally.