I had the same issue, pushed up both my drip tray and grate. They replaced the deflector and the new one did it too but slightly less severe. Only pushes up the drip tray this time which still causes grease flow problems.
I had the same issue with my new Trailblazer but was able to fix it by lowering the minimum feed rate. I just cooked ribs at 250 for 6 hours and had no issues. Maybe this would resolve your problems too?