Have a rebuilt, 1 hour on powerhead, 1987 70hp Evinrude that idles OK in neutral ~1000 rpm but when trying to set the idle speed to 725rpm in forward in the water, revs decrease to <400 within a minute or so, then it dies. When I turn up the idle adjustment screw to 725rpm in forward, the engine will hit almost 2000 rpm when I pull it back into neutral. Am running 25:1 break-in fuel mix, carbs rebuilt as part of rebuild), new inline fuel filter, new fuel hoses, SS hose clamps & fittings. Have checked for air inleakage with WD40 spray. Have done a synch and link, idle timing set to 4 deg ATDC, correct plugs installed. I'm fresh out of ideas at this point. Is this problem temporary just because the new powerhead is still tight and I'm running twice the normal amount of oil in the premix? Maybe I just need to run it some and loosen it up? Any thoughts much appreciated.
