i have a 1997 tj wrangler 2.5 4cyl i love the car, i get 7 mpg, no lift regular 30x9.50 15 tires. i have fixed a lot of things on it.... map sensor, radiator, alternator, i had a tune up i changed one of the o2 sensors and i lose power while driving and i get black smoke when i rev the engine and no one knows what the prblem is hellppp?????????