Basically whenever i hit a bump or expansion joint my front end has this loud "thump" to it. If you drive steady all you will hear is the tires singing and the vehicle tracks straight. I already replaced the lower ball joints and the idler arm. What else could cause this?

 

Upper balljoints, although it shouldn't be as loud as a lower, a broken swaybar link, possibly a loose or worn shock (but that's stretchin' it). You should also see if your hood hinge bolts are loose. This can cause close to the same sound as a ball joint only up higher.