I have a 25 hp 3 cyl 2 stroke evinrude, motor starts and idles great off start then after a minute or two of driving or I exceed 3/4 throttle engine will start jerking then engine will start running rough I will come to a stop and motor is idling terribly I will attempt to throttle and will get no response,then I will shut engine down and restart and engine will run normally again until I attempt to full throttle. Please help first time engine owner.