Idles very high. My 50hp 2006 Honda 4 stroke idles very high. When I use the handle end on a screwdriver and tap either of the other carbs linkage, it idles back down where it should be. The idle will stay that way, till I throttle up and then back to idle position. Then, once again it idles very high. The higher I throttle up and return to the idle position, the higher yet it seems to idle. But once again, using the screwdriver and tapping on either of the other 2 carb linkage drops it back to the correct idle. Making idle adjustment with the idle score doesn't make any diference. I don't want to put on the lake for fear of damage to the lower unit, when I throttle up and put it back in idle position. Please help.