1994 Ranger 2.3 Thermostat/Heat Question

[virgamanda]

I have a 94 ranger with the 2.3 liter engine with only 78,000 miles on it. My temperature gauge reads just above cold and there is very little heat. Occasionally the gauge will move up to the half way point which is normal then there is plenty of heat. I replaced the thermostat this morning with a 195 degree one and there was no change. It still reads just above cold on the gauge with little heat. What else could be causing this. The antifreeze in the system is in good condition with no corrosion and all the hoses get warm when operating temperature is reached. What could be causing this overcooling problem. When i rev it up really hard, the temperature gauge will move up near the middle point and heat is very good, then it goes back down...maybe water pump. Please Help!!!

[jd-autotech]

i would do a coolant flush. and flush out the heater core through the heater hoses back and forth til you get clear water