Blower works fine,, heat comes and goes... any thoughts??

 

clogged heater core. Are u still running on the Dex-cool crap? It has a tendency to turn to mississippi mud and clog up a heater core.

 

How is your coolant level? If you disconnect the heater core and run water backwards through it, it can clean out some junk. It worked wonders for mine.

 

With the engine at operating temperature, grab the heater hoses and check their temperature. If they or even one is cool, then the heater core is blocked.

You also could have a bad "blend door actuator" which is the electrically driven gear that adjusts how much air goes through the heater core.

You also should check if the controls for where the air is sent, defrost, heat, or vents, is working correctly. If not, then you might have a vacuum leak in the hoses under the hood in the engine compartment.