The best way to solve a situation like this is go to the graph editor . . . go to window>animation editors>graph editor

In the graph editor, you can see what each key is and how it is affecting the overall animation, and edit it. If you have a key that is way out of line with what you want you can just move it or delete it. Learning how to use the graph editor can save you a lot of time.

Make sure you have the object you are animating selected when you open the graph editor, or select the object you are animating after you open the graph editor.