I have a 2007 Outlook with 115k miles on it. Today, my wife was driving it and it didn't shift correctly. I came home, took it to get the codes scanned (engine light on) at the local O'Reilly and got the following codes P0751, P0752, P0877, and P0989. I have read a little about this and thought of changing the transmission fluid first. Any thoughts would be greatly appreciated as I cannot really afford to replace the transmission.