I live in Colorado Springs and I can tell a difference from Missouri to Coloardo. I cheat and use a bbq guru for my long cooks such as brisket and pulled pork. I have to take the meat off and shut down the egg about 10:00 PM because of bears. Then I finish the cook the next day. 225 degrees on the temperature is not the same as at a lowler altitude, so I think it take longer to get the meat up to the final temp. But also the temp goes up faster because the fire does not have to heat the moisture in the air because we do not have any moisture. I agree to clean out all ash and use new lump. You will have to play with the daisy wheel and the lower vent. The bbq guru makes the cook so much easier.
I have been using one for several years, Love it!!! I just recently received a DigiQ from my son and it seems to be more accurate. Can't live with out it for long slow cooks. I have to start early in the morning and can only cook until sundown because of the bears, I live in Coloardo.