no power when in gear

i have a 1997 altima and when its in park or neutral it has power and you can rev up the moter all you want,but when you put it in gear it has hardly any power and wont go above 1500 rpm and bogs out any suggestions?

Have you checked the mass airfow sensor out? How's the intake boot? Or spray some carb cleaner against the intake and listen for a change in idle.