EF300iesb Generator is 11 months old (50 hours) runs good when started for about 30 - 40min then cuts out (I hear 1 or 2 carberator pops and then idles really low and has a jerk about every 1 to 3 seconds but does not die completely it seems to be mis-fireing I think? Could the problem be a sensor? Oil level and over load light do not come on. Cleaned carb and fuel lines, new spark plug checked valves. Still can't seem to locate issue. Any advise or suggestions would be greatly apperciated. Thanks, Eric