Toyota help needed.

[wrnchplr]

I just got an 88 runner with a V6 manual. there is 224,XXX on the clock and she runs good. the problem I am having is when sitting at idle the heat goes cold on the front heater but the rear stays hot. I am thinking a heater core is going bad, but a shop I called said that water pump. Just looking for some advice here. Has anyone had this problem and if so how did you get it fixed?
Thanks Dave.


:EDIT: I have back flushed the cooling system and relpaced the thermostat.

 

[Coreshot]

If the rear heater is anything like the old Land Cruiser ones, they have engine coolant flowing through them all the time. Mine was always hot, but you could turn the fan on and off.

 

[wrnchplr]

That is how the rear is. I just need to find out why the front won't stay hot when the motor is less then 3,000 RPM.