HELP!!!!!!!!!! If you are a mechanic or fellow jeep owner (hope you dont have the same problem) my 1997 jeep wrangler (4cyl) keeps fouling o2 sensors. The computer says the engine is running both rich and lean at the same time up and down stream. The Jeep runs rich, horrible gas mileage, smells of unburnt gas and sooty exhaust. It runs better after warmed up and over 2500 rpm ( replaced plugs, o2 sensors two times already, fuel bar, air filter, diconed battery, reset codes) motor is new rebuilt on 20,000 miles. After replacing o2 sensors runs great for 3 days then back to same symptoms and fouled o2 sensors. It runs but ratty. What is causing these o2 sensors to keep fouling???