The usual suspects are the cancel switches. Since yours is an auto, there will only be one under the brake pedal. They can be adjusted, I understand, but I haven't done so. The older models worked off vacuum, so there were some components to check/adjust, but the newer ones are all driven by a control module. I'm not sure what can be diagnosed with those.
My '93 CDE also has the cruise inop. It used to work sometimes, but cut out. It's on my list of things to fix during the summer...
Mike when it used to work sometimes and now doesn't do anything at all. I'd suspect the control unit under the dasboard. Seems to be the way how most of them die. First working fine then sometimes not, and finnally dead.
When the cruise started being intermittent in the first place, almost everything was replaced: the cancel switch, the stalk and the control module. The module wasn't new, but it was from Goldwing, a fairly reputable Saab recycler here in New York State.
I had similar problems with my '92 2.3 FPT. Sometimes it engaged, sometimes it didn't. Even when it was engaged it would suddenly dropout, not a pleasant experience around the M25 in the fastlane!!
In the end my local SAAB specialist [Cromwell SAAB in Beckenham, Kent] replaced the control module and it's been fine since then. Off to West coast of France in 2 weeks, driving from Le Havre to the Vendee so hoping it will take some of the strain off the trip with 3 children in the back!