Is the check engine lamp on? Or has it come on since the problem is occuring? If so this will have to be looked into prior to proceeding, as the codes stored in the computer's memory have priority over any other diagnostics. Now these vehicles have a problem with their CKP (crankshaft position sensor or reference sensor) this sensor fails when hot and causes the symtops you descibed it can set the check engine lamp when failing, but in most cases it doesn't. It is a fairly inexpensive sensor and i would recommend replacing it if you don't have the means to test it. The correct method of testing requires the signal to be traced using a good quality lab scope. Another common failure is the ignition cassette (Ignition Module) this item more commonly fails causing missfire on the engine and eventually the engine will not start. The cassette has no diagnostic procedures and usually is obvious to a trained Saab technition when it fails, I would wait for better symptoms if the CKP sensor doesn't work, this part costs approx. $500.00 at the dealer and an additional 1.5 hrs to install.
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