I used a friends protank 3 and found the same result, he was running it on a VV at 3.8V with a brand new 1.8 atomizer. I used a protank 2 for a while and never had a vape feel like that unless i was utilizing a 2.2 ohm coil atomizer. With a dual coil at that voltage I expected much more, the shop manager said they have already stopped ordering kanger tanks because of how finicky they have became over the span of higher mass production. I would suggest trying an atomizer swap or perhaps if you have the knowledge and tools to do so to simply recoil and wick the atomizer to your liking.