My '84 GL is running very rich.  Mileage is 10 mpg at best.  Blows thick
black smoke when loaded (i.e. under acceleration).  Down on power in general.
 Idle speed is eratic but does not stall (yet?).  Been driving her daily
under these conditions for months.
Things I've done:
Checked/adjusted ignition timing.  Was retarded.  Now correct (at least
close).  Made no difference.
Measured fuel pressure:  36 psi at idle with vacuum connected.  42 psi (at
any engine speed) with vacuum line disconnected.  If increase engine speed
(with vac. connected), fuel pressure decreases (yes, DECREASES) to about 32
psi.
Swapped out the air flow meter for another (used but serviceable) one.  No
significant change in behavior.
Examined the spark plugs.  All four were equally black and sooty.
I also cleaned (with electrical contact cleaner and, in case of ground
connections, emery cloth) and exercised all of the connections I could find
on the engine management wiring harness.
I plan to measure the Temp. II sensor resistance tomorrow.
An observation:  I noticed that the position of the AFM wiper is about 20 or
25% "open" with the engine idling.  This seemed surprisingly high to me, but
I have no reference.  Could be normal.  Anyone have any input?  I also
adjusted the CO adjustment screw (under the plug on the AFM housing) and this
had no real effect on the position of the AFM wiper.  Had a small effect on
the quality of the idle.

I did a mechanical rebuild on this engine two years ago (did not do anything
to the fuel injection/engine management system).  It ran fine and gave me 19+
mpg overall fuel mileage until this problem cropped up a couple months ago.

Thanks for any suggestions.

Mike

I know that there's probably been several discussions in past on this
subject, but I am new to this list and I haven't figured out how to search
the archives by subject.  Maybe someone can help this non-savy computer user
in this respect.