1995 Subaru Legacy

Engine Cooling problem
1995 Subaru Legacy 4 cyl All Wheel Drive Automatic

I started car on morning - let run approx 10 minutes to melt ice on wibdoa as normal, heater still blowing cold after driving less than 1/2 mile started to heat up. Turnede around and came back, heated rapidly. Have already replaced thermostat, radiator, & head gaskets. Still heating up while blowing cold air thriugh heater. Water pump is not leaking or making noise, shaft felt good without ay play. Probably a blockage somewhere in water system but hoping someone has run across this and can tell me wher to start looking.
April 25, 2010.

Double check the thermostat if okay try bleeding the cooling system don't work get it block and pressure tested

Apr 27, 2010.