cruise control oscillation

I posted this before but have new symptom information. The cruise will oscillate mainly when it's cold and also the needle on the speedo is bouncing (slightly). (like if going 50 will move rapidly between 48 and 52)

I think it has something to do with the needle moving back and forth b/c the vaccum hoses were all good and it does not do it when the speedo is smooth and steady.

Any ideas what would cause the needle to bounce like that? Is the '92 instrument cluster electronic or have a cable? :?:

My Galant does the same thing sometimes when I am cruising (but without cruise control). It doesn't bother me, so I ignore it.