So about a year ago I replaced my compressor. However I believe it was aftermarket. A year later and I started to have some of the similar issues. These issues are: the car revs aggressively in humid or extra hot conditions- more often with the AC running. This tends to only happen when the car is idling however it chills a bit if I throw the gear into park and/or hold the break pedal down with all my might and power. The turbo gauge jumps at this point. Is it a dying compressor? Dying turbo? Transmission? Help!!
Idle Air Control (IAC) valve, maybe. Usually they tend to starve the engine, making it run very rough but who knows what it may do on a Saab.
You can usually take them off and hose them down with carb cleaner. Very rarely do they need replacing.
I forget how the IACV valve is mounted on a Saab (had two myself) but on most cars they come off by loosening two small bolts and disconnecting a rubber line. Almost always they sit on top of the engine somewhere, easily accessible.
They clog up over time and do weird things to your idle.
Good luck.
Vacuum leaks and EGR malfunctions can cause this too. Another common cause of surging at idle is if the manual idle speed engine adjustment was used to “correct” what was really a different problem, rather than fixing what was actually not working in the first place. This confuses engine computer to no end.
Assuming your car is a 2.0 Turbo 4-cyl, the IAC valve is buried under the plastic engine cover. Once the cover is removed, you’ll see it just to the left of the throttle body assembly. It’s a small silver cylinder (about the size of a large aspirin bottle) with two 1inch diameter rubber hoses attached at one end, and a 2 wire connector on the other end.
Press down on the wire retainer and pull to disconnect the electrical connector. Then loosen the hose clamps and undo the hose connections (these may be in tight spots, I recommend a small 1/4-in ratchet with a 7 or 8mm socket on a short extension). The IAC motor should then slide off a metal peg, and you’ll have it free.
Use carb cleaner or similar and spray down both hose connections. You’ll be amazed at how much black gunk comes out of one.