Hello--my 544 recently had all the symptoms of a fuel delivery problem, especially starting from a stop: faltering, stumbling, stalling, etc. Finally, looking under the hood at night I noticed a carbon track had formed on the coil top, bright blue arc was visible under even light revving. Cleaning the contacts and applying a dollop of dielectric grease helped immensely--but it's a stopgap, since once the coil is tracked, there's no repairing it, needs to be replaced. Check it out in the dark! Best, Nate