You using atomizer and cart? If so buy the precut blue foam stuffing for 510 at strictlyejuice.com - much less likely to give a burnt taste and easier to pull out to do a full fill (fill juice cup 1/2 way, insert tapered end of the foam, press the foam into the liquid to wet it, reposition top of foam at top of juice cup, top off with 2-3 drops so it looks damp. Then just top off when needed until topping off doesn't help (probably needs another full fill then)
Blue foam is also super-easy to wash if the flavor gets yucky - just take it out and hold in running eater then pat totally dry.
BTW - how low have you been using your atomizer and have you ever cleaned it? Does it look dirty and gunked up? That can cause burnt flavor too. Buy spare atomizers and then try cleaning the one you are using.
And try cartomizers - standard resistance Boge soft-caps are good
And off topic - Juicy Vapor's Butter Rum Caramel - omg very nice