1998 Ranger, one heater hose hot the other warm, fan works, Water runs through heater (disconnected lines, ran water from a hose through heater), but heat is at it's best luke warm. What do I check next?

 

There are a couple of reasons the heater core may not be giving off as much heat as desired.
Among them are; the heater core may allow water to pass through, but may be coated internally not allowing the heat to get to the outer fins.
Another could be the heater core is air bound which is easily corrected by loosening the upper heater hose while the engine is running and pulling the hose back off just far enough for any trapped air to exit.
A questionable water pump could affect this, as well as a restriction in the heater hoses. I would try to make sure all the air is out of the core before trying anything else , it's a quick fix and not difficult to do.

 

Could be worn impellers or bad fan clutch on your water pump. This would keep the water from circulating properly. Do you have any temperature fluctuation with your temp gauge? This would also be another sign that the impellers or clutch is bad on your water pump. Could also have a bad heater control valve. This is connected to the heater hoses under the hood.