What’s wrong with my Technique??

[NHDE57WOODWIND]

I have a WOODWIND. So I am baking potatoes on High for an hour ish. Then I want to Reverse Sear a Steak. Sooo I open lid, turn temp down to 225, let the temp drop some say 50 ish degrees, close lid (still have not put steak on ) watch the temp on th grill, when it gets close to my 225 I put steaks on.

PROBLEM IS the Grill seems to just keep losing temp and never seems to fire back up... So I guess I am doing something incorrect???:(