Pontiac Repair: Heating, head gasket, air pockets

Question
The other day I asked you about a heating problem with my 1996 Pontiac Sunfire. I thank you for a fast and to the point answer to my problem. After reading it and acting to your answer it is still running hotter then normal.But now read this. A guy at work said that he heard that if the heater core is a little plugged up the returning coolant going back to the thermostat housing can't help to open the thermostat and it may not open. What would be your thought's on this. I was thinking also about that pipe with that vent screw on that return if it could also be plugged up. Have you ever heard of this also causing the engine to run hot. Again thank you for your time and any reply to this question  NORMAN

Answer
I have yet to see that happen on one of these. When the engine is running feel the heater pipes one should feel really hot and one just a bit cooler. If so the core is not plugged. if one is cold and one is hot then yes it could be plugged or have a air pocket in it. if your getting constant air pockets out of this I would really start to suspect a head gasket issue. It should bleed the air out easy enough. if you keep getting air in it it has to be comming from somewhere. head gasket is a likely suspect.