I know on my Weber that if I choke down the vent at the bottom and open the top wide open it slows down the cooking. Wonder if that would help you. I can then close it down if I wanna reuse some charcoal later too. I have cut way back on my amount of charcoal I am using also..I was using way too much. Pam .☆´¯`•.¸¸. ི♥ྀ.
I know that works on Weber's, I have two (WSM & WSJ), not sure if that can be done effectively on a PBC. The pictures below show the vents on a PBC, the first one is the bottom vent that is supposed to be adjusted according to the altitude you're cooking at, in my case 1/4 open for altitudes up to 2000' MSL. NOTE: This picture shows the vent as closed at it will get, there is still some air gap and I did not cook the ribs in this configuration, I had it 1/4 open as recommended in the PBC instructions. I may try my next ribs with the vent as shown and see what the results are.
The second picture shows the vents the PBC has on top, the four holes, two on each side for the rebar to fit in. The only vent adjustments that can be made on the top side is to remove the rebar, which I'm told will increase the temps inside the barrel and/or offset the lid to provide more air that will also increase the temps inside the barrel.
I know that I can stuff foil in the vents to completely shut it down and save the unspent charcoal for the next cook. I need to fiddle with the air vent some more to slow down the cooking time on the ribs. Good thing I didn't use my Kingsford Compitition for this one.