New 300 has BAD vibration

[300HP32168]

I have a new 30" Suzuki 300 installed on a 2005 Pro-Line 24 Sport, by a dealer. I have a very noticeable vibration just above idle (lots of idle zones where I live) and at the sweet spot, 4000-4300 rpm. Yes I have tried several props. Left and right hand.

Dealer GM has ridden with me several times. At first he was concerned but he is giving up and bored with me and my issue. Last time out he changed his tune and told me it was normal at idle speed and cavitation at 4000 rpm's. They are going to try prop #4 as son as they get one in.

This is my 4th Suzuki. I know it's not a normal vibration.

I've had the boat almost 5 weeks and I am losing patience. What do I do next? Any ideas?

[Bamahemi]

Pics of installation? Maybe bent center shaft or prop shaft! Mine is a 300 have 67 hours and happy, almost 3.7mpg, using a 3x16x17p prop on 25' blue fine CC! Call Mike at International Marine in Boyton Bch!