SmokerJim, which PB Pellet Grill do you have?? Most have P-Settings...
During the preheating process of going from Smoke mode up to 350* degrees, it’s normal that your grill will over shoot a bit and then come back and settle at 350* degrees. After 15-20 mins and your grills temp is holding steady at 350* degrees, then you’re ok to set your grill to your desired temp. For Me, during the Summer months, I’ll preheat at 300* degrees for 15-20 mins, but no lower then 300*... and during the Fall and Winter months, I’ll preheat at 350* degrees for 20-30 mins to help allow my grills temp to settle in at 350*. Preheating is so important for the
PitBoss Grills, but doing so will help cut down on having temp swing issues especially during the cold seasons. To have temp swings of 5*-10* degrees that You’re having is very good too. It sounds like You have a rock solid grill. Good luck and enjoy.
Pellet Pro Austin XL and a few more mods... in SoCal and Always... Semper Fi