You never have the device sit, cool off, then not fire or fire anemic?
I have just a G2, but I can't say that I have ever experienced that. I know its been mentioned, but I see a couple of things that may need to be addressed.
1 400-450 deg would be the bottom floor temp to get anything usable vapor wise. I have found this to be true with every TC mod I have used.
2. If you are removing or even of the Atty that you are using becomes even slightly loose, this can and probably is affecting TC for you and that Atty. This causes the device to become our of sync with the Atty. I posted about a loose feeling 510 earlier in the thread. But basically, you need bottom out your atty to ensure it is tight against base of device.
3. Your FSK curve seems off from what you are using. Kathak is is in the 60 range, SS is around 11, I use 15 personally for my builds.
I hope this helps in some way. After all that, it's quite possible that you have a malfunctioning device but I also think a Lot more troubleshooting with base/known setting should be done.
Good luck, there are a lot of knowledgeable folks in here, much more than I in this thread.
3.
Sent from a random device, most likely a LG V10