Hmmmm - tough one - I would try a different topper. I am a big Innokin fan and have several of their models - not cool fire.
However - I don't like any of their toppers - top feed means one needs to turn device upside down or sideways to saturate wicks.
U might want to try an inexpensive EVOD or evod clone, mini-protank, boge cartomizer with or without tank - bottom fed
Single coil is not the issue IMHO - I use exclusively single coil bottom feed toppers - make my own micro coils 1.5 ohms and vape at 8 watts. - with great success and vaping enjoyment. I rebuild EVODs, T3s, mini protanks, RTAs, RBAs, and RDAs.
Different toppers work for different users - many like the iclear series - unfortunately for me the four I have that came with itaste devices are in a permanent timeout.