Your carb has trash in it, and trash likely caught in the inlet needle and seat. Clean the garbage out of the carb and float bowl and orifices.

The 2 stroke mix didn't mess up the carb, dirty gas messed it up. I have been know to run some 50-1 mix through my GCV160 when I am out of non mixed gas.

A great engine but just give the carb a careful and complete cleaning.Take your time also and when you put everything back together let us know what happens

thanks guys,

I finished what you guys suggested, the mower still idles up and down. I took some pictures so you gay can see my work, not very good pictures because with my phone but... I also took a video but I have to convert it first so you guys can here what it sounds like. Everything on the mower seems pretty clean. There is a new spark plug that I put in, changed the oil but still it goes up and down. BTW the carb didn't seem dirty at all other then on the outside.

Here is a link that might be useful: {{gwi:133348}}

Here is the video

Here is a link that might be useful: VIDEO

Our mower had similar problems this spring, and the engine rpms steadied out after running the machine with carb cleaner added to the gasoline. It takes several hours of operation for the carburetor to clean itself out, the results are not instant. You might have gum deposits in your carburetor that are hard to see.

Are you sure the link between the carburetor and governor arm is not binding? It may be bent.

yeah there is no binding or anything bent.