Do not close that damper. Air flow is necessary for a hot fire. All you will do is make the problem worse. Instead make sure you fire box is clean of all ash. Open all vents all the way. Build a hot coal base with charcoal, lump is hottest. Add a couple of logs if you can when coals are hot. Use chunks if logs wont fit. Put a third log on top or inside of the fire box if possible. Add that log when fire starts to drop (about 1 per hour or so). Only adjust the intake vent if too hot. Keep the exhaust wide open.
Your choice of fuel is also important. As I said, lump is hotter than coal. Oak and mesquite is the hottest common wood. Fruit woods are cooler. Smaller wood burns hotter than large but must be added sooner. They key is to get that baby hot and then reduce air flow with the intake. Also realize toy temps will drop when you add that big cold bird so get it too hot at first. Heat sinks like a water pan or fire bricks help maintain temps too. Fuel + airflow = heat.
Good luck man. Hope this helps.
Weber Platinum Kettle, Weber OTS, Meco square grill, ECB, a WSM, a cool fold up camping grill, a Blackstone flat top camping stove, The MOAB, and now the proud owner of a YS640, MOINK.
Smoke on Brother KC
Father of the Fatty (the name) 4/20/04 on the BBQ Brethren with inspiration from Brother parrothead.