Nissan Repair: air/fuel mixture adjustment, air fuel mixture, gasoline leak

Question
How do I adjust the air/fuel mixture on my '95 Nissan Pathfinder XE V6 2WD.  The tailpipe is very black which tells me the mixture is too rich and the gas mileage is very bad for a supposed higher mpg vehicle.

Answer
Hi Dave -

The mixture adjustment is obtained by a small screw on the intake throat, however, if the tailpipe is that black, I am thinking it is something else, like a misfiring plug or vacuum leak, gasoline leak.

How is the car running?

Please get back to me -
aloha
calvin