No fuel will make your engine with that prop turn faster....from 5% to 15 % nitro may increase up to 400RPM when much. Forget what manuals says about power....they are not reachable with the props the enignes are intended to be.

If the man on your LHS is a modeler....he should know that... I don't trust your LHS for advise [:@]
11K RPM sounds good for a prop in the range I guess...what prop are you using? maybe your prop is on the heavy side...but for a bushed engine I think is ok.

If your needle valve became unresponsive, it can also mean that your carb has junk, make sure you can blow through the tubing into the carb...look for something that is clogging the fuel path.

Keep us posted

Jorge