Try putting a drop or 2 drops of peppermint oil into whatever oil you are pulling with, that stopped it for me.
I find I am more toxic in the morning than the evening. I use to gag and almost throw up until I used the peppermint oil. Then eventually as I became less toxic it stopped and I stopped using the peppermint. Though I like the peppermint, its clean and breathy fresh. I still use it for that mint fresh taste sometimes.