Well then something is up with your setup, or you are still vaping the coil at too high wattage (suggested wattage is just that-- a suggestion. Going over will definitely cause issues, but being below recommended wattage can often provide a good vape AND longer coil life.
You've gotten lots of good advice. Mine would be to either give up on that tank (it seems it doesn't seem to be working for you) and/or take the setup in somewhere to help you get up and vaping it without a bunt taste.
Best of luck,
Anna