swampfox

My 89 22r fuel mileage dropped about that much and it turn out to be the air diverter valve in the air intake snorkel. It is the one that pulls hot air off the exhaust manifold to improve cold weather performance. Mine was pulling hot air all the time. I just plugged the vac line off and have not had any problems for a couple years now.And the mileage went back to normal.