mercury 100 hp 1998 170 hrs runs and starts great except after running enough for thorough warm up and sitting while fishing for an hour or so on hot day. will start right up and run for several miles fine then starts to miss. tach may drop 500 rpm then it will miss and surge for 5 or 6 miles then will smooth out and be fine as long as I don't stop for a long period of time and hot soak. Dealer has changed ignition switch boxes, plugs,cleaned carbs, adjusted carbs, no change have 2 tanks, does it on both. any ideas? thanks whaler1
