I HAVE A 1988 EVENRUDE 140 .. I HAVE GOOD SPARK AT IDLE AND WHEN I INCRESE RPM'S AND SPEED ,CYLENDER STOPS FIRING AT ABOUT 1500 RPM'S I HAVE GOOD SPARK AND 125 POUNDS OF COMPRESSION. I HAVE ALREADY CHANGED COILS SPARK PLUG AND CHECKED CARB ,ALSO CYLENDER WILL INTERMITENTLY FIRE OFF AND THEN CUT...