Go to options, then to to the Game tab and go to Advanced Options. Look for the Joystick drop down menu if you have a controller plugged in and change the ScaleRUV and ScaleXYZ value (it's 1000.000000 by default) to something more manageable (about 60~120 should be fine). If you need need to invert Y axis for looking, while in the Advanced Options go to the Advance drop down menu then go to Raw Key Binding and look for the binding "Axis aLookUp speed=-2". Change the "-" next to the equal sign to a "+" and you should have inverted Y axis without inverting your movement.

Now I need help with using the triggers on an Xbox 360 controller and stop the game from using the "Pause" command when I try to map "ShowMenu" on the Start button.