I have an 88 special that runs smoothly at all throttle settings but idle.Seems to cough every5-6 seconds.Sounds like a pre-ignition condition to me.Hooked up a timing light and it read 4deg at idle.Anyone know what it should be at idle(on muffs,in neutral).I turned the idle speed screw to 10 deg and no cough.It did increase idle speed a little,but without a tach,I'm not sure how much.I believe it should be at 500-600 idling in gear in the water.