De-Acceleration When Driving on 2001 Volkswagen Golf

When I'm driving (gas tank is full), the accelerator idles on the freeway. I don't take it out of gear, and there are no warning lights. I have regular maintenance checks, and all the parts are up to date.

I have a manual transmission at 131,770 miles. I just replaced the timing belt and water pump.

Does anyone else have this problem?

Asked by for the 2001 Volkswagen Golf