Ok I would assume the carb is not dialin good ...I’d clean the plugs ...then do a lot of low rpm running and take offs ...like stop and go traffic is ...or just idle it at home making sure it don’t get hot ...for 30 minutes or so and check plugs again to see if low rpm is the problem where it’s running rich ....my guess it is ...the plugs we’ll tell you ...that be my first move ...