Just a thought on my PG500 from a brand new unit and smoking a brisket. To keep it short, the fire was going out and the auger was filling the fire can full of fuel pellets. After the temp cooled all the way down to 129degrees, the igniter would start and go to a large roaring fire in the pit (since the fire box was full of pellets) going to 450 before it would burn down. While looking into the auger in the dark ( at 2am not by choice), I noticed the pellets in the auger were glowing, so I ran the temp way up just to clear it out. Emptied the hopper to make sure it wasn't in the hopper ( found several blackened pellets) and went back to bed. I woke up in the morning and watched it cycle from fire dwindle out to 375-425 a couple times ( one of the cycles filled the smoker and the area with a lot of smoke..... then it ignited with a muffled poof and blew the doors open).
Called CS and spoke with them and adjusted the LHT and the HHT, at that point I learned it was not an automatic one setting does all on the controller. I moved the LHT to 15 and the HHT to 65 which kept the temp much better at 225ish without large temp swings.