Bbq guru problem

Unplug it and let it reset and you should be good

As mentioned above, unplugging it will reset its cook memory. I was told or read somewhere once that if your guru has to blow the fan for a long time to get back up to temp, the guru learns that it needs to blow past the temp set point so it doesn't fall below the set point. I don't really like that feature, but it is in its programming. Unplugging it and leaving it unplugged will reset that memory of the guru.

If you don't feel like going through the extreme effort of going outside and unplugging it, rebooting it from your computer or smartphone also works.

I've started setting mine for 20 degrees lower than my target temp to account for its tendency to overshoot the temp I want.