Accelerates Spontaniously

I have a 99 Passat GLS V6. It's been a good car, but recently it has started to intermittently accelerate. I'll be cruising down the highway at 120kpm and it will start to creep up to 130 then 140, ven if I take my foot off the accelerator. The 1st time it happened, I just wacked the gas pedal and it settled down. Since then, it has happened several times when my wife has been driving (on highway and around town) and the only way she can correct it is to turn the car off. We took it to VW, but they couldn't duplicate the problem and their computer diagnostics showed no problems (what else is new).

Any ideas??

Hi, if it's a drive-by-wire car could it be a noisy throttle pot?
Phil

VR6's are well known for problems with the throttle actuator valve. Some people have rectified their problems (usually check engine lights and poor idling) with a thorough cleaning of the throttle body.