I've had this annoying issue since I bought this car and annoys me when I see another thirdgen with perfect lines.

Let me preface by saying I've never done any body work before.

If you notice in this picture you can see where I'm talking about at the bottom


Now the bumper I believe is new. It had no decals on the car (did that myself) and it hasn't been in a wreck according to the history. What would I do to correct this? I know the under panel is also falling because it cracked off the screw.

 

A better close up would be better,are you talking about the fender aero panel or the front Fascia ?
I know when I had my car done over,I returned a Brand New Aftermarket Front Bumper Cover,couldn't get it to line up properly(gaps between the fender & Cover,

 

It looks like its almost bigger ? :/ and where they meet up the bumper bows out more than that fender

 

That could be from jacking it up in the wrong place, it will bow out in the middle of the fender and tuck the lower end in. I replaced my fender because of that,but I would fix those under panels that you mention 1st and see if that's the cause of your problem.

 

Jacking it up at the wrong spot causes issues back by the door/fender gap. He's having an issue with the bumper cover's molded in GFX and his factory piece.

There is damage on the original GFX...is it just smashed up? If the bottom of the fender is pushed in, it'll take some of the bow out of the GFX. You might need to do some massaging of the front bottom area of the fender to get it closer. These cars can be a PITA to get all lined up, due to the lines of the panels, and all the pieces. You usually have to start at the door gap, and work your way forward.

HOWEVER...if that is an aftermarket bumper cover, you are in for some more work probably. Those things, along with fenders, rarely fit well. A lot of times they require a good bit of work to make them perfect. If you have limited body work experience, and you arent planning on painting the car, you might just try loosening things up in that area, and getting it as close as you can. Also...paint the dang chipped off area. It will draw way less attention to it.

J.