general problems of the 2001 Toyota Highlander

2001 Toyota Highlander purchased new. About once a year it accelerates on its own. Reported problem to Toyota dealer in 2002 or 2003 - have receipt. We can stop the car with firm pressure on the brake. In most cases when we put the transmission into park the engine continued to race at high rpm. I can't remember all incidents, but believe that in some cases was able to slow the engine down by keeping my foot on the brake and putting the car back into drive. Other times I turned off the ignition. When I restart the car it is fine. Most recent occurrence was Sunday 4/18/2010 in parking lot of a&p on south avenue in clark or westfield, NJ. My wife was in the car with me. I had been driving the car for about an hour. The last half hour was on the garden state parkway at 55+ miles per hour. Was off the parkway for less than 5 minutes when I made left turn into a&p parking lot and another left in the parking lot. Driving less than 15 miles per hour. Then was almost stopped as I was about to turn left into parking space. Noticed the engine rpm seemed a little higher than normal and I became more cautious and made sure my foot was firmly on the brake pedal. The engine rpm began to increase rapidly. I pressed on the brake pedal as hard as possible and was able to keep the car from moving forward, but the engine would not stop racing. I put the transmission in park and the engine continued to race at full throttle. I turned off the ignition and the engine stopped. Restarted the car after a minute and it was fine. Don't believe I was pressing on the gas at the same time as the brake because the two pedals are far enough apart that to do so my foot could only be halfway on the brake pedal. In that case when I press hard my ankle starts to twist. I am sure my foot was centered on the brake in this incident because I had time to prepare and it felt firmly in the center. I don't think the gas pedal was stuck because I had been driving very slowly immediately before the incident.