Need help determining the right idle speed for an '83 140 Johnson. Once the engine is warm it idles at 12 to 13 hundred rpm but sometimes it kicks down to 5 to 6 hundred. In forward the lowest rpm is 5 to 6 hundred. Where should the idle be set for normal conditions and should it be kicking down to 5 to 6 hundred? At that low rpm it is hard to shift into gear without stalling the engine. Thanks