Left house and proceeded downhill on gravel driveway and then turned left onto main road which is a hill rising approximately 200 feet over.5 miles. At top of hill let off accelerator but the speed was still increasing. Tapped accelerator, pulled floor mat away from gas/break peddle area, tapped accelerator, whole time depressing break with both feet. Finally cut off ignition at approximately 55 miles per hour. I coasted the car backwards with engine off and turned it around. When I restarted car the engine was at idle and I drove it home without depressing accelerator. When I checked car at home I observed that the rubber thimble covering throttle cable at throttle was deteriorated. I pulled the rubber thimble off and observed that the rubber had entered the throttle cable housing and was the cause, jamming the cable at the accelerated speed. I cleared the cable and housing of the embedded rubber and car accelerated/decelerated normally. A precursor to this was that my gas mileage had decreased dramatically on the last fill up, Saturday, from 19mpg to less than 12mpg. I was looking for a leak and had intentions of bringing it into the repair shop on Monday (tomorrow).

- Earlysville, VA, USA