I have an 181/2 Searay with a 115 evinrude on it (1969) The motor runs rough, and will not make power. It starts fine but sounds like it is breaking up.I cannot get much speed out of the boat. Took the cover off the motor and played with a lever ( manual calls it a throttle lever) on the right side of the engine ( when looking at the motor while in the boat). The lever is vertical and connects to something else under the flywheel by means of a bent rod. I hope I am making sense. Anyways we played with this lever and the motor ran perfectly. Lots of power. After fishing and on the way in we tried to play with this lever again but this time we couldnt get the motor to run right. The motor just barely ran. Couldnt get any speed out of it.Like 'i said, we fooled with this lever and the motor ran like a new one, but tried again and couldnt get it to run that way again. The motor has been checked out at a dealer ( compression etc) I dont want to talk in circles. The motor seems to be in fine internal condition because when we did get it to run right that one time, it ran perfect. I thought the choke might be closing up, choking the motor. Or maybe there was an ignition problem. Anyways, if anyone can help, would appreciate it. 