96 Dodge Stratus

I have a 96 Stratus ES and for the past 4 years or more the heat hasn't worked. Not even motor heat from the vents. My water pump was replaced in August 06. I was told it could be the thermostat. A different mechanic said the water pump wasn't working correctly so the thermostat couldn't be checked thoroughly. My car hasn't run hot since the water pump was replaced and I've taken the radiator cap off to see the water boil and flow which leads me to believe the pump works. I purchased a Haynes Repair Manual to help me understand the coolant flow and I realized the overflow tank plays a major part. I lost the overflow tank cap long ago and used foil and electrical tape to cover it for the time being. I think I had warm air this morning. Could this be so????

Is coolant circulating through the heater core?
Is the blend door opening?

if it was the thermostat stuck shut then the engine would be super hot and radiator wouldnt be

if it was stuck open it would take a really long time to warm up the engine

but all hoses would be at least real warm

and the radiator too

im working on a 99 breeze right now that i was told needed the heater core replaced but i am not so sure now after looking everything over on it this mornign

the lower rad hose is cold, the temp guage is 160, the upper hose and engine are hot, and so are both heater core hoses, and the HVAC panel assembly is working properly and changing vents/defrost locations great

i am putting a new thermostat in it right now,

and if that doesnt do it then im going to reverse the core hoses

and run some new fluid since it is dirty dark green old looking