My Super Z with 87 hrs has just started to have an engine speed that surges constantly when it is not under any type of load. The engine will not idle at the normal low speed as it did when new but it will idle at higher speeds as long as it can surge. I do not believe the governor sensitivity adjustment is the issue here. This is a cv740s-0017 engine. (It does Not have EFI.) Thoughts anyone? TKS.