I did try backing off on the smokestack a little at a time. It's not the fire in the firebox that's the problem. I can get that hot enough to melt the paint off the sides. I'm have trouble transferring the heat over for some reason.
The reason is because you insist on using charcoal rather than wood splits. The charcoal has had almost all of the moisture burned out of it, so there aren't a ton of gases being produced when it burns. Wood splits, on the other hand, are full of water (good wood splits have about 15-20% of their mass being taken up by water), so when they burn they give off a TON of steam as well as NO (Nitric Oxide or Nitrogen Monoxide) and CO2 (Carbon Dioxide). These gases moves very easily in warm air so this makes it exceptionally easy for something like the drafting system of a smoker to pull those very hot gases from the firebox, into the smoking chamber, and out the exhaust stack. This is why the offset works so well as it allows for a very clean fire and it the drafting system pulls the air into the smoking chamber and out the exhaust pipe.
As others have already stated you'll need to remove all the bull**** attachments / "mods" you've added and start cooking with the splits. You'll easily be able to get your smoking chamber to 400F with just a few medium sized splits. I also noticed that you said you couldn't get them in your area and that's just not true (if you are located in Flint, MI as your profile suggests).
https://flint.craigslist.org/grd/6162022338.html
Craigslist is your friend when it comes to wood for your smoker and I have found I have the best luck when I search "firewood" rather than something like "bbq wood" or "wood for smoker." Make sure you're getting hardwoods and NO pines, spruces, or furs.
Here's an old post from this forum which lists a ton of woods for BBQ... just make sure what you're getting delivered is on this list.
http://www.bbq-brethren.com/forum/showpost.php?p=492877&postcount=2
I'm pretty sure I posted this video in your previous thread but I'm posting it here again so that maybe you'll watch it and learn something.
[ame]https://youtu.be/0Azfvya6n4Y?t=15[/ame]
Good luck man... we all want you to succeed and enjoy your offset smoker. EVERYBODY is telling you the same thing for a reason... because it works. Cheers!