I have my text moving from out of the screen up into the middle but have realized it is not perfectly centered. When I center the text it does not also center the movement of my text so it no longer goes straight up and is now a curved, erroneous path. Is there a way to center the keynote position as well?
Are your keyframes properly placed and linear?
Without seeing your layer properties and knowing how you are animating the text it's impossible to tell what's going on.
Generally you would use the Centered Paragraph style to center text and then adjust the baseline shift to line the anchor point up with the part of the test you want to have in the middle. You would position the text with the position property with an X value of half the comp width.
To animate the text you would add a text animator and animate position. This will give you a second position property for the text and allow you to move your text with a range selector.
The things that will throw this off are usually just simple user errors and poor techniques. If you can't figure out what's going on then please give us a full resolution screenshot of your project with all the modified properties of the text layer revealed. Just select the text layer and press the u key twice, take a screenshot and then drag it to the Reply window of this forum so we can see what's going on.