Airflow is the likely culprit.
Make sure the meat is not blocking the airflow with an overloaded shelf or being up against the exhaust.
Bandera needs to breathe
Also, check that the meat is not real close to the temp monitor.
I assume you are using something other than the door thermometer??
I also assume you have a couple of inches under your fuel grate for incoming air??
Good Luck
TIM
__________________
"Flirtin' with Disaster" BBQ Team (RETIRED)
FBA and KCBS Cook and Judge.
Former owner of a WSM, a Smokey Joe, a Charbroil Commercial gasser (junk), the legendary "StudeDera", a FEC100, a Fast Eddy PG500, and Sherman the Wonder Trailer.
Just sold Yoder YS640 due health
New Ninja Woodfired Grill for Christmas 2023