Don't use the top vent to "hold in heat". It is there to let the smoke out. You do not want to get into the habit of smoking with the exhaust restricted or worse, closed. Trust me on this.
I am speaking from experience.
You need to learn how to manage the fire and correct the airflow problem at the intake. If you are getting good airflow at the intake and your fuel is not getting choled with ash, you will have no problems keeping temps up -- as long as the wind is not blowing. Even a slight breese can cause problems for these thin-walled smokers. You may want to consider building a wind break.
Probably a little bigger than you need but you get the idea.
Keep working at it, you'll get it.
Dave
You need to learn how to manage the fire and correct the airflow problem at the intake. If you are getting good airflow at the intake and your fuel is not getting choled with ash, you will have no problems keeping temps up -- as long as the wind is not blowing. Even a slight breese can cause problems for these thin-walled smokers. You may want to consider building a wind break.
Probably a little bigger than you need but you get the idea.
Keep working at it, you'll get it.
Dave