I personally start the pack at 260, and work up to 340
I know you're talking F, not C, since 340 C is way past combustion. A true temp of 260 F won't get you any THC. You get traces at about 285. And you get clean THC (no toxins) up to about 370 F.

anything past that leaves a nice coating in your mouth
I don't find that to be the case, even with high temp vapor.