Song a as playing and then slowing down like 50% and then playing and going back and fourth like that.
Moderator Edit: Changing title for clarity
Does this happen with a particular station? Are you connected to any other device, such as a Bluetooth speaker?
In the meantime, I would uninstall and reinstall the app to create a new connection with Pandora. This will also clear the cache as well.
To do that: