I have a 1984 944.  The car has been out of service for a few years
and and after an engine rebuild I am trying to get it to pass
emissions in CA.  I took it to one place and without even testing the
car I was told it's running to rich.  I usually have a good nose for
this kind of thing but of course I am questioning myself.  Is there
any way to adjust the mixture.  In addition, there is a screw on the
top of the air flow sensor that takes a 5mm allen wrench.  Can anyone
tell me what it is for?

Please help,
tjbabar