hey guys ....could use some help. my boat seems to be running really rich. The transom and swim step are black after any long run. I changed the air cleaner to the new plastic style and replaced the oil breather. I'm running A4's and only able to reach 3650 rpm with a light load.Butch at oceanside marine center recommended A3's is the place to start. I am thinking injectors? Have you guys tried A3's? Seems like the boat will over-rev.... thanks for the help.... oh by the way I have a AD41b W/290dp