Accelerator Stuck problems of the 2003 Lexus GX470

In 2007 or 2008 the accelerator on my Lexus GX 470 stuck in the wide open position. I had floored the accelerator to pass a truck and when taking my foot off the accelerator the car would not slow down. I was able to apply the brakes with much effort and turn of the ignition. The floor mat was not part of the problem. I then restarted the car and it drove normal. I took the car to the Lexus dealership where I purchased the car new, which is Lexus of mishawaka, indiana. They inspected the car and said they could find nothing wrong and that it was probably the floor mat. It was not the floor mat. I traded the car in at Lexus of mishawaka in November of 2008. I no longer own the car.