Alternator power suckage!
 

So when I turn my headlights off my idle rpm goes up about 300. Is this normal? I just tightened up my alternator, could it be too tight?

I assume you mean you tightened the alt. belt.

Only a loose belt will effect the electrical output of the alt.

An over-tightened belt will ruin the belt, alt. bearing, and the tensioner bearing.

The computer controls the rpm thru the Idles speed control valve, by monitoring various sensors and load conditions.

So first check and clean all the ground wire connections you can find, starting with the battery posts.

If you don't find any obvious problem areas along the way, and it still does it, you may want to have the charging system tested.