I meant to post a couple of days ago, but your MAF may be your problem. The MAF communicates with your O2 sensors to control fuel / air mixture. The MAF is extremely difficult to test. You can find some videos regarding the procedure on youtube, although the videos are not Saab specific. I saw a cable program recently, "two guys garage" where they discuss the MAF in great detail and a faulty one turned out to be the cause of a rough running issue. I think it's easier to just swap it out to see if that cures the issue.
2003 Saab 9-5 Aero B235R
Sport Wagon 2.3T HO Manual