1995 Mercedes Benz SL500

Electrical problem
1995 Mercedes Benz SL500 V8 Two Wheel Drive Automatic 160K miles

Hi my SL 500 has recently begun to down shift on its own rendering the gas petal useless, unless I press it way down. When car in neutral, it revves on its own. But, when I restart the car, it resets, as it were. Then starts the same thing all over again. This has happened at various speeds. Could it be my transmission?
January 31, 2010.

If it revs on it's own in neutral, it may be the accelerator pedal possition sensor is defective, have it scanned to be sure before part replacement. Could also be mechanical, like stuck throttle plate.

Jan 31, 2010.