[quote name='MrrNoName' date='07 October 2010 - 04:01 PM' timestamp='1286463095' post='100168']
i had this EXACT problem on my zetec fiesta last year. happened exactly as you described.. revving when dipping the clutch and holding the revs when you release the accelerator pedal. I scanned it for codes and found "Throttle Position Sensor out of range" when unplugging the battery to reset the ECU the code AND PROBLEM was gone, but when driving it again both came back after about 1 week of driving.
I found that when unplugging the throttle position sensor the car ran rough but the problem was gone!
when researching the problem I found that it was not uncommon but seems to be a ghost in the machine, and is caused by one or multiple sensors giving incorrect values. I started by replacing the throttle position sensor (as it was right at the front of the car and cheap to purchase) unfortunatly this did not cure the problem.
other people mentioned that it could be bad/corroded wireing causing too much resistance and lowering the voltage (effectivly changing the value of the sensor) but i never did get to the bottom of the problem, i ended up just unplugging the battery for 10 mins once a week
sorry cant be more help