Fire rose too fast.
Have used a smaller pile of coals to start with all vents open.
Once the pit temp approached 175 I shut down 2 vents fully.
My WSM runs 300*(empty water pan) on one vent wide open.
As a result: 2/3rds to 3/4 open on one vent works for me.
Cooking at Mason-Dixon BBQ Services
Lang 84 Deluxe Kitchen known as "The Glamazon" , Custom Klose Backyard Chef... of Snot, and a 22.5 WSM
Lang 60 Mobile - The Damsel II, Lang 48 Patio - The Damsel, Bubba Keg Grill - RIP, Double Barrel Smoker and a BSKD