Technical explanation
WARNING: This page is about a different car, the 2003 Saab 9-3 and 2002 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
The cause of the problems is one of the potentiometers (pot.1) in the throttle body. The throttle will then make brief movements in the closing direction. In this case, irregular idling may be noticeable or there may be surging when driving on motorways. The fault is not significant from a safety standpoint and does not affect exhaust emission control.