Engines require constant tuning in 1:1 cars the computers update the tune many times a second. In rc you don't need to go that deep, but they do need to be tuned daily due to the fact that many things from temp to humidity can affect the tune. If you didn't changeth te tune in a week that would cause the engine to be so wrong it wouldn't start. It sounds to me like all you needed to due was reset the needles to factory and re tune the engine for performance.