When warmed up motor turns and starts most the time. At this point, motor will die if throttle not applied. Apply throttle to bring RPM's to 1500. Motor RPM jumps eratically from 1500 to 3500 RMP on its own for up to 1 min. misfiring for duration then idles normally. Can then pull throttle back to normal idle position. Have replaced fuel filter, seperator, fuel pump pulsating hose, plugs, primer bulb has pressure. When put on trailer at end of day, motor starts normally, stays running, idles but will only misfire a few times per min. Mechanics have checked and cleaned coils, still does it. 3 days till grouper season opens back up. Any thoughts before I drag to the shop and spend a fist full of dollars???