I'll join the club and say it's too lean on the high end. Possibly to the point of the cylinder and ring being toast. You could go back to factory settings but I do not think it will do much good. Maybe even check all the bolts

The weird thing is, I just ran across a brand new one this weekend on a WH Edge that was very close to the same symptoms you are seeing, but no dead sticks and head temps in the 165 - 170 degree range. When cold, it had tons of compression, when warm, it felt as though it had very little, it started like clockwork, but the prop would not windmill and it was turning an MSC 22X8 in the 6800 -6900 range and it was rich as shown by the head temps. I'm wondering if the newer ones have a clearance issue between the ring and cylinder. I have two Da50's in the low 3000 serial number range and neither seem low on compression after warm, even when they were new