Thanks for everyone's responses, which were extremely helpful. As mentioned a few times, the air needs to be able to pass through the charcoal which is totally the issue. In a perfect world, I should drop the whole chute down ~6-8 inches but think I may have an idea bc that's a LOT OF WORK!! If I add a steel plate that spans the entire width of the firebox towards the back and that is a few inches higher than the bottom level of where charcoal is, this would force the air to go slightly up the chute and come down on the back of the steel plate that was added before going into the cook chamber. I would need to put a canopy above this steel plate inside the chute so no charcoal would spill in but leave a large enough gap so the air can easily pass through.
Any shot this would work?