I have a 1997 Saab 9000 CS 2.3 light turbo with 125,000 miles on it. It runs very well and has been well maintained. The only problem I have is that when I come to a stop, the engine occasionally starts to rev itself up (up to 2000 RPM). This happens over and over again at a stop light then quits as I accelerate through the gears then starts over again at the next stop. The problem disappeared this summer and has begun to set in with the colder weather. Not sure if the weather has anything to do with it. Any ideas??? Thanks.
It sounds like a vacuum leak. With the car being 10 years old, vacuum lines and plastic connectors and tees could become brittle and crack or break. With the problem only showing up when cold, I suspect a bad vacuum switch or a cracked line or connector. This will be hard to find, depending on how many lines are on the car. It could also be a leak in the air intake hose between the MAF sensor and the throttle body.
Vacuum leak or Idle Air Valve problem. You might swing by a local AutoZone, Advance Auto, Checkers, etc. and have them pull the codes to see if anything is there since there are a few things related to vacuum leaks and the IAC that could set a code.
They will do this for you free.
Check codes and inspect for vacuum leaks (especially around any valve cover grommets, etc.) before messing with the Idle Air Valve. Sometimes cleaning the IAC works and it’s a bit pricy if you have to buy one.
http://www.autopartswarehouse.com/mmp/saab~9000~idle_control_valve~parts.html
Also make sure the oil filler cap is on tight and the dipstick is inserted fully into the tube. SAABs can be a bit cantankerous over simple things like this.
Thanks for the advice. Now I know where to start looking!