Black smoke is too much fuel. Do tha compression test and then repeat but with a tablespoon or so of oil in each cyl. If the rings are bad the compression will go up with the oil in there. Shake the pcv valve, and if it rattles, it's good, but I would replace it anyway as they only cost a couple of bucks. You must have a breather to go with the pcv. Oil smoke that occurs mainly @ idle is usually from the valve guides, under open throttle is usually rings.
