Well here is my experience. If your throttle plate is stuck, no amount of soaking will help it. What you should do is remove the base and use a small torch, like a propane torch to heat around the shaft. Do not use a lot of force trying to turn it but let the heat do the job. It will free up. Then you can clean and rebuild the whole thing. The rusted base can be soaked in rust remover. They are fairly simple and work quite nicely even though they take a lot of bashing from Carter fans!
