2005 GTP bubble in heater core

2005 GTP 112K Miles

My check engine soon light came on so I stopped in to see what code it was throwing. Thermostat stuck open. Ok, I buy a thermostat and sure enough I noticed the car wasn't running as warm as it should.

So I changed the thermostat last weekend and yes indeed it had failed, replaced it and tried bleeding but the coolant level never really dropped and no air at the bleeder screw. While driving the temp was right where it should be, then after about 10 minutes the heat suddenly went from hot to lukewarm. Oh great... I assumed a bubble had moved to the heater core.

Since then I've tried bleeding it multiple times, even jacking the front end up as high as I can. All it's got me is a lot of coolant all over the place and the heat is still not hot.

I cannot express how tired I am of dealing with this. Does anyone have any suggestions bleeding a 7th gen 2004-2008 GP?

Thanks

Consider that the loss of heat may not be due to air in the cooling system. Are you confident that the water pump is circulating the coolant? Is the coolant temperature where it should be? Might it be a problem with the venting such that outside air is no longer directed through the heater core?

Just offering other possibilities. Good luck.