Mitsubishi Repair: 89 montero v6, poor combustion, o2 sensor

Question
to start, good afternoon.my montero has a ticking sound when on and it spews smoke when on idle and even alot more when i excelerate. it picks up speed fine,until it hits about 2500 rpm then i starts tugging and the rpm start bouncing. after 2600 rpm it smoothes out.can anybody shine a little light on my problem... thanks

Answer
Victor,
If the smoke is dark gray or black, that would indicate you have a lot of unburnt fuel.  This could be caused by poor combustion, faulty O2 sensor, or bad catalytic converter.  Also have your ignition timing checked.  If your timing is off or perhaps you have some bad spark plugs, that can also cause a stumbling problem.
Good luck!