i have a 98 gs400 and been having the same problem so i went to my mechanic and got a diagnostic and got a p1120 code (accel. pedal position sensor) he called the dealer to find out how much would the job be for me and was told approx. $500. I went home and called the dealership to make an appointment i was told that it is a recall and it will be replaced free of charge. My appointment is for tomorrow so i will keep you updated on what happens to see if it the problem was fixed.