Speedometer sometimes sticking on 30mph

[TurboSlacker]

This is a weird speedometer problem that is not like most posts addressing shaking needle.

When accelerating or decelerating the needle sometimes stays at 30mph for appx 5min then all of a sudden goes to the correct speed. I've tried to make it do it under different conditions without success.

I did lube the speedo cable to see if it fixed it. No go.

Anyone seen this issue or have ideas for me to try?