either your density through the coil is off, or have a loose wrap, causing a hot spot, or a combination of both.
When you pulse the coil, does it glow from the middle out?? Pulse and squeezing coil can help even it out. But as long as the coil is working fine, then it's simply play with the density of the wick through the coil, till it vape right.
Vape long and Prosper.!!!!