Saab: Hi fuel consumption, robert bentley publishers, rich fuel mixture

Question
I have a Saab 94 900 SE with a very rich fuel mixture. I'm thinkihng either o2 sensor or / and fuel pressure regulator?
Normal idle s/b about 900, it's close but, I notice the idle
will drop to about 1200 while off gear, off throttle and remain there wihile coasting until a complete stop.
Perplexing and expensive.....

Answer
As noted in my profile, my hands on expertise is limited to the pre- 1990 900's. I can, however, offer some general comment. You are likely correct in thinking about fuel pressure or the O2 sensor; The latter is the more likely culprit. You should be able to self-diagnose the suggest getting a good book (Robert Bentley Publishers) or alternatively, subscribe to an internet site<www.alldatadiy.com>, ($25/year/vehicle). The website has the most complete info I know of!
 By doing it yourself, it need be neither perplexing NOR expensive, but quite rewarding.
                 Hope this helps,

                            Jerry