I recently got the Aspire Pockex. I've primed them and let them soak in liquid too. I never let the tank get lower than half. I've also been taking gentle drags, not chain vaping. No matter what, a few hours later these coils give off a plastic / burnt taste. I've tried at least 4 different coils. I'm using clear 70VG Menthol EJuice. This is driving me crazy. Any advice?