Sudden drop in performance and gas mileage
I have a 2000 Jeep Grand Cherokee 4.0, 6 cylinder. My car, intermittently has a sudden drop in performance and gas mileage and the exhaust fumes have a very distinct & strong odor as if it is burning very rich. My gas mileage goes from about 20 mpg (highway) to about 4 to 6 mph. it will remain this way for a long time and then suddenly, it reverts back to running normal. Can any suggest a possible cause and fix?