As PigCicles said, leave the top vent open. Without enough airflow, the food will taste like creosote. Check your thermo with another one, most stock thermos are not real accurate.
A quick 3-2-1 primer. First 3 hours, ribs in the smoker with smoke being produced, spraying each hour. Next 2 hours, ribs wrapped in aluminum foil packets with some of the liquid you used to spray added to the packets. The ribs "braise" for that 2 hours, making them tender. The last 1 hour ribs out of foil, in smoker with smoke, add BBQ sauce the last 30 minutes if desired. Saucing earlier will allow the sugars in the sauce to burn.
I prefer a 3 to 1 mix of apple juice and Captain Morgan's Original spiced rum for the spray and liquid in the pouches. Others use apple juice and bourbon, others use straight apple juice or even pineapple juice. You will find your personal preference after a little experimentation.
Also be sure to remove the membrane from the bone side of the ribs, as it prevents smoke and flavor from penetrating both sides, and it is very tough to chew.
Hope this helps!! Keep trying, and keep asking questions!!
Take care, have fun, and do good!