I do my ribs 275-300 Back ribs take 3-3.5 hrs until they pass the bend test St Louies 3.5 -4 hrs, Full spates 4-4.5 hrs. I'd check my thermos if I where you. are you recording the cook temp on the grate or some where else. Grate temp is the key to good "Q"
I never met a Cow that I didn't like with a little Salt & Pepper! Certified PORK-A-HOLIC