Have a good look at the sensor loom lines immediately below the front plastic engine cover, as this is easily damaged, multi point connection between plugs and sockets made not quite secure by independents poking around underneath the bonnet unsure of where things are exactly.
Listen out for a soft ticking/hissing sound from the engine, which can be a manifold issue for the turbo i.e letting air in and out at the wrong place.
All though the car was serviced 3 months ago, who was it done by? was it a Kwikfit special or a Saab dealer or an independent Saab specialist?
What was the mileage that the level of service was based on? this is often an indication as to what has actually been replaced or checked on the car.
I am assumming that the engine diagnostic light has remained off so far?
Let me know how you get on,
