Yeah, the K3 is like a large eGo... 1200mAh battery and 1.8 Ohm coil (with 2ml tank).... I suspect it vapes like a Nautilus with 1.8 Ohm coil (MTL only)
Since you don't have any real adjustments, and I don't think coils of any other resistance are available... the only thing you can control is the juice. @VapeMama suggested moving to a thinner juice, and that will be my suggestion as well. Most of MTL all-in-one devices prefer juices that are of a specific thickness... The Templar AIO likes 50/50 (PG/VG) juices, but can handle 30/70 if you don't chain vape it. I'm willing to guess the K3 is more like the vape of a Nautilus (the coils even look like the Nautilus BVC), which works best with thinner juices... 70/30 (PG/VG) to 50/50 max. Some "clear" juices can be a bit thicker, but 60% VG is about all they can handle (most likely what your problem is being caused by).
Try a thinner juice, or add a few drops of PG to your existing juice (a few drops of distilled water in the tank also will thin a thick liquid), and see how that works out for you?