I purchased a 2002 Sonata with 30K miles. The engine runs very smooth, but it appeats to be very rich. The tail pipe is wet with black soot. The engine does smoke or appear to use oil. The gas mileage is very poor (less than 15gpm is town). The check engine light is NOT on. ANy suggestions on what to do to address mixture issue?

 

I suppose you had it tuned? Correct plugs, oil filter, correct weight oil, timing, vale check, air filter?