Sounds like an airlow problem, have you tried loosening your tank by a quarter turn, a bit more airflow will improve juice flow on bcc type tanks - I actually get something similar with the Kayfun - not enough juice so it vapes a bit dry, I'm still dialling in the airflow for this new setup...
i also use 2.4ohm and vivi nova but at which voltage do u run this at?Lower ohms means you can vape at a lower voltage to achieve the same power. Power mode on the Vamo automatically adjusts voltage to maintain the wattage you have set, when you change the ohms of your coil. I vape at 9.5W using 2.4ohm Vivi Nova.