Help! I've got a iGo that I've been using for about three months and it's been great. Until yesterday. I'm vaping away and think "This doesn't taste right." I pay closer attention and notice that the vapor temperature and taster have fallen off. I try the carto on another battery and get the same result. All of a sudden all of my cartos on all three batteries are not heating up to where they have been. I checked the voltage and I'm getting 3.8-3.9v and the resistance on the cartos looks right in the 1.8-2 ohm range. I am getting taste and vapor, but just less than I ever have before, and at a suddenly lower temp. The cartos vary in age from ones that I've been using on and off for a while to ones that are only a couple days old anda re all fully topped off. Any clue what's going on here?