I came from Akorn to Louisiana Grill, so can relate to this. I replicated my high temp cook from Akorn and couldn't get there fast enough. Like others said, you will need to add more fuel and don't start closing the vents until few degrees past the required temp.
If your charcoal / wood have a mixture of small and large pieces, the small will burnout faster than the large. This would mean if you wait too long, then your fuel has significantly reduced. I noticed this to be the case with Royal Oak. I found a charcoal chimney / fire-starter to be extremely useful to avoid such burnouts.
In the Akorn I noticed the air entering is quickly super heated because of the metal compartments, whereas in the ceramic the flow is cooler but the quality of radiant heat is very good.