I have a 1989 140hp johnson outboard that won't idle. If you get it started and catch it just right it runs great at high RPM. From 2500 RPM and up it runs great but from aprox. 1500 or lower it caughs and quits. Last year I replaced the CDI and VRO pump. Recently I have check the timing and compresion and have cleaned the carbs. The compresion and the timing were both fine, any suggestions would be greatly appreciated.