Anyone notice within the last year your fuel filter isn't lasting more than 3 months.Always used Shell fuel(2.89 a gallon). Whats the stutter below 1000rpms. All new filters,Lucas treatment in the fuel. Only thing changed is 4" exhaust, BHA, starwheel bumped up a little. Never touched the pump timing and still getting 18-19mpg. 286,000 miles today. Is there anyone in Southern New Hampshire that knows how to time these pumps?Would low idle stutter be more fuel flow than timing? Thnx steve