Saab got this great idea called hydraulic (oil filled) motor mounts.  They go a long way toward reducing vibration and shock, but they just don't hold up well, particularly if abused.  There are three mount points - one at the lower left and two at the lower right - and one "anti-torque" point at the upper right.   The torque rod is plainly visible at the rear of the engine compartment, next to the alternator.

The lower left (transmission) mount is solid rubber and is not prone to failure.  On earlier cars (through 93?) this mount is pressed into a circular boss in the transmission cover, and it looks like it would be risky and difficult to try to change it in the car.  On 94 and later models, a semi-circular strap can be removed and the mount can be changed easily.  The lower right mounts are both hydraulic, and the front one is particularly prone to failure.  The torque rod has webbed rubber bushings; the front bushing in the torque rod is prone to failure.  Failure of the torque rod bushing can lead to lower mount failure, and vice-versa.

Symptoms: The shifter jerks fore and aft as much as a couple of inches on shifts, acceleration or deceleration.   You can sort of check it by getting on and off the throttle in 3rd or 4th gear at 35 to 40 mph (maybe an inch of total movement is normal, but normally it will be a somewhat damped movement, not clunky or extremely jerky).  A broken torque rod bushing is another symptom of a bad right front mount.  The right rear mount may or may not need replacement.

Checking for bad mounts: Engage the handbrake securely.  Put the car in low, rev the engine just a bit and partially pop the clutch repeatedly (don't be abusive about it).  If the shifter slams all over the place, suspect the mounts.  As mentioned previously, the shifter will move quite a bit even with good mounts.  There's only one sure-fire check (non-return to this page).

Preventive maintenance: Townsend Imports recommends reducing the amount of travel to prolong mount life.  My modified Townsend mod (non-return to this page).  Driving gently will certainly prolong the life, but gentle driving isn't necessarily what the Saab 9000 is about.  If motor mount life is of paramount importance, I would recommend putting in a rubber damper as Townsend suggests, and then adding a solid spacer to cut mount travel to 1/4 to 1/2 inch.  I have not done this on a permanent basis, but I tried it temporarily and did not notice a significant increase in engine vibration.  As I said, I would recommend this only if long mount life is the primary issue.