Hello, I have a 115 hp 2-stroke on a 24 ft pontoon and I can not get it to go over 19 mph. Everything on the motor and boat are as they should be. One problem I notice is when I "throttle up" my throttle lever, wide open hits the dash and I have to hold it in place or it will back off as we cross the water. I am wondering if there is an adjustment at the throttle lever box???