Last weekend I smoked some ribs for 5 hours and overcooked them. They were ediible and still taste good but definitley overcooked. Should I trust the temperature gauge?
What I do with mine is put a temp probe through a raw potato and used that to get the temps at the upper and lower cooking grates. Be careful to not let the probe touch any metal. I found a small spread with the bottom grate being a bit hotter. I think I saw that post and I was surprised at how charred they were for 5 hours so I would definitely test your lid guage against a known good therm.