I am not sure about the Stevia, but here is what I have tried recently to make it taste better. I never let it get to a boil. When I see steam start coming off of it, I take it off the heat, let it sit for 10 minutes and then strain it. There is a fine line with this stuff where it seems like if it gets too hot, it tastes sooooo bad!
It seems to still be working with this new cooking method. My low back pain has gone and stayed away and I have cloudy urine first thing in the morning which I take to be a good thing.