f300 throttle adjustment?

[hastingsS]

First post hoping someone might be able to help. I have a single 2011 f300 with command link mounted on a GW 268 Islander which replaced original f250, prop is the SDS 15 pitch 'salt water' which was recommended by the Yamaha web page. Also installed Bob's Machine jack plate. I have never been able to get my rpm's above 5400 and was thinking I needed to change my prop but now I am wondering that it might not be my prop but instead I am now thinking if it could be that I am not getting maximum output on my throttle? I have good acceleration up to about 5100 -5400 but I just cannot get any more and still achieve performance and maintain good mpg. So, is there a throttle adjustment that will give me those extra rpm's up to 6000?
My dealer that I purchased the motor from is out of business so I thought that I would ask for some real world advice. Thanks

[99yam40]

I have good acceleration up to about 5100 -5400 but I just cannot get any more and still achieve performance and maintain good mpg.

What do you mean by this statement?

[hastingsS]

99yam40,

That means my throttle is pegged all the way down.

[rodbolt17]

whats the model number?
the F300 was made in both a V8 and a V6.