Dar, you theory may be correct, but it may not, and all the clues have not been presented and thus so far we are simply taking it for granted that the HS adjustment is done correctly. He did not mention anything about HS needle adjustment to help in the diagnosis, such as "even when I set it obviously far too rich on the ground, it still quits in the vertical" or "I set it 500rpm back from peak, and when I hold the nose up and pin it, there are still a few rpm left when I give the fuel line a quick pinch" or "when I hold the nose up the rpm pick up a whole bunch or seems erratic" or anything to do with engine behaviour on the ground. Therefore it seems logical that people will bring up HS needle adjustment to eliminate the obvious first.