The model you describe 42250 is not a model Saab, but I find an Aero model with the 2.0 engine. The gearbox light being on indicates a problem and you will need to have the vehicle scanned to see what...
A new ignition coil is a very likely suspect for this issue. I would recommend enlisting the assistance of a YourMechanic technician to diagnose your issue. (https://www.yourmechanic.com/services/engine-is-misfiring-inspection) Have the technician switch the suspect ignition coil with a known good one...
I would have a technician inspect your rough idle (https://www.yourmechanic.com/services/car-idle-is-rough-inspection). He will probably also check for codes on the computer. It may be the air temperature sensor malfunctioning if it idles rough only when it's cold. You may be able...
Having your car run fast like this sounds like a frustrating experience. Let us get you pointed in the right direction so you can drive your car worry-free. The symptom you are experiencing with your vehicle sounds like something called...