A couple things...
When coils are new they will often taste metallic. I soak them in alcohol and swish them around a few times once and a while to get out any oils etcetera and leave em sit a while...then shake them out and let them dry completely before using.
Also, if you are getting dry hits there are a couple reasons why this may be happening:
juice is too thick (high in VG)
Or..you need to tighten up your lip grip on the drip tip to be sure you are drawing liquid in as fast as it's being steamed...
HTH