I have a 2000 Olds Silhouette that has taken on a life of its own. I can drive down the street at 50 mph without pressing on the accelerator because it is idling so high. When it is in drive with my foot on the brake it is at 1500 to 2500 rpm and in nuetral it is at 2500 to 4000 rpm. I can get this to resume a closer to normal rpm measurement by restarting the car several times until it resets itself. The TPS has been replaced although the computer is still reading this error message. There has to be some sensor that is bad and causing this problem, please help.