OK so she is getting somewhere around 8mpg if its only 100 miles on. tank.
I do a see. few useless responses but we would like to help her get it fixed. you may as well change the fuel filter anyway at this mileage, but the MPG she is getting means it HAS to be running rich or has a fuel leak somewhere.
also you say it runs great for a four banger.... that may be true, but does it run great for that engine?