I am going to recommend some steps that has helped me along the way:
Get you a bottle of Biotene, rinse with it twice a day after brushing your teeth
Increase your water intake. Even if you already drink a lot, drink a bit more. Plain water, tea, coffee, and flavored waters don't count.
Leave all juices alone that have vanilla or custard.
Do this for 1 week. You can do it.
Set up a clean build and try just one. After drinking a glass of water. You are trying to cleanse your palette, don't cloud it with flavors until you try your vape.
I had to do this for some flavors that just were not there for me in my first year. Year 2, I would just vape unflavored for a few days. Year 3, I no longer have need to do any of these things. I don't get Vapers Tongue anymore.
Just to add info, I do use Biotene have since I got mouth/lip piercings way back when even though I don't have them anymore. As far as water intake besides the mornings/ late evenings if I drink any more water I will be in danger of drinking too much. I even use the neti pot at least once a week and have tried rebuilding and rewicking to like these juices but none of it works.
As soon as I load up The Virus, Wakonda, GCD or the fruit vapes it's awesome. And I get all the flavors I hear people talk about, with the others it just doesn't happen.