FYI.....Hope this might help somebody. I've been having a problem with my 2000 for several months. Idle drops, then goes back up again every 2-3 seconds. Has been steadily getting worse. Got so bad that my lights were dimming on the drop. On the advice of a Volvo mechanic I took the throttle body off last weekend and cleaned out a lot of gunky build up around the butterfly. Runs dreamy smooth now.