422 dyno fail
As
@PRH said. It smells like a valve control issue. I just watched “engine masters” show on valve float and it was very insightful. The exact cause of the lack of control could be many items including just weak springs, but it could be long, heavy lifters, flexing push rods etc. While I am not a builder of motors, the up and down of power through the chart tells me that it is not merely choked or cam timing that causes it to fall flat. Perhaps it is electrical that causes the blipping of power as the rpms ramp up.