With key on in park my speedo reads 46mph. and while driving normal its at 80+. Why and how do i fix this?

What is your question?

I just bought my 2003 Sedona and was told by seller it was the speedo sensor. I replaced that but didn't fix it. It drives fine idles fine just burns rich. With key off it rests at 21mph. Any ideas?

What makes this problem better or worse?

Nothing

How long has your 2003 Kia Sedona had this problem?

Since before I bought three van