I have a 2000 50 hp 4 that is driving me nuts. have had intermittent trouble with coughing, hiccupping at *****ing speed, stalls ocassionally when I give it throttle. Have had all carbs adjusted with mercury tube deal, checkd compression, replaced thermostat, fresh gas, new plugs, new bulb and gas lines (removed gas line connector - now straight shot to filter/carb...). It sat for a couple of months over winter - took it out two weekends ago (trailered it for about 30 miles) - ran best ever...not a single issue. took it out yesterday - coughed, hacked, stalled, hard starting...rough idle one minute - next smooth as silk. (Weather was identical both days). Water seperator is clean. In the yard with FW flush attached - cranks up easily when cold - warmer it gets, rougher it runs...then sometimes smooths right out and purrs, the - no reason - back to rough - seems to be okay at high end .....help
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