Most of the time - and yes, I say most of the time - you have one, if not MULTIPLE things wrong with your mixture. If I said "try an AVOCADO-24 RTA", I'd be going way out there for some. It has got to be the most fun tank to work with and the flavor I get from is is phenomenal. BUT! Before you go out there and blow a huge chunk of change on gear... a word of advice when doing DIY - NOT ALL VG, PG, NIC, and FLAVORINGS ARE CREATED EQUAL! I prefer FlavourArt flavorings when I mix. I mix MOSTLY 6-9mg nic levels too. 6mg for dripping / tanking and 9mg for tanking ONLY. I've made many good (and just as many BAD) liquids. DIY mixing is a test of patience. Keep at it though... it's frustrating, but eventually, you'll find what works for you.
As far as what's making you cough or has a "dusty flavor" to it - change flavors, lower nic levels, and use less PG - more VG if it's making you cough and has a "dusty" or "dirty" flavor to it. Also, I find that boiling my mixtures (in the bottles - inside a pot of boiling water) AFTER I mix them aids in mixing the compounds together very nicely. After I boil the bottles for a few minutes, I take them out and let them cool to room temp, and test taste them on an RDA or a carto (which I need to order more of) that's been thoroughly washed and dried and / or rinsed under hot water with a fresh wick installed. Also note - BEFORE wicking a fresh atty, make sure you wash and dry your hands THOROUGHLY! As cotton has a tendency to absorb oil from your hands. Use a good soap, a clean towel, and warm water. It helps. These things have helped me. Try them, if it still tastes "dirty" - try a softer flavor. Like vanilla (or mint - as it seems to help cleanse that nasty taste off my taste buds).
