Volvo: bouncing idol, housing software, electronic throttle

Question
I have a 2001 XC V70 and the car is in park, sometimes in drive, the idol will be about 900-800 RPM and will spin down to about 500 RPM, before ramping up to about 1500 RPM independently.  Thoughts?

Answer
Patrick,
Maybe an electronic throttle housing software fault. Call your dealer and ask about the latest updated software downloads. Have the VIN ready so they can check your vehicle. There also might be a fault code posted to read that will show a faulty part. The dealer can read the faults.