01 Jeep Cherokee 4.0 I-6 has Luke-warm heat, not hot.

What is your question?

The colder it gets the colder the heat is in the car. Only comes out Luke warm. Thermostat is new, coolant level/quality is good, heater core was just flushed and ran clear after 2 gallons of distilled water. Operating temp gets to a range of 185 to 195 and stays, no overheating issues. Heater core inlet hose is hot, outlet hose is colder. All fans and blend doors work. What could my problem be????? What do I do next????

What makes this problem better or worse?

The colder it is outside, the colder the heat is.

How long has your 2001 Jeep Cherokee had this problem?

A few weeks.