My bet would be vacuum line first. Go out, get a bottle of engine starting fluid (or other similar alcohol-based spray bottle) and with the engine idling, spray on the vacuum lines. If the idle suddenly changes, you've found your culprit. If they're badly cracked and/or worn, I'd still get them replaced, as it's a cheap/easy job, and it can't really hurt any to hold vacuum.
Does it always idle high? Just have trouble dropping idle? Any other noticeable conditions - noises, vibration/shaking, scents, or other changes?
Wednesday, October 20th, 2010 AT 6:10 PM