Where to Find a Line of Code

So I am troubleshooting some issues and have discovered through the pingdom speed test an issue that is causing a slower than good load time. There is a request for an image file (header.png) that does not exist, result in a long wait (10-22 seconds) and then the 403 error.

I am not an expert on wordpress; however, I would imagine that the code trying to call this image would be found in the CSS stylesheet for my theme. I am using the Genesis framework with a custom child theme. The Genesis theme is brand new and was never tampered with – just a fresh install to support the child theme.

I have searched through the child theme’s stylesheet and every other php file associated with it (there are only four) and there is not a single instance of header.png.

I have reviewed my plugins one by one and none of them would ever call an image – they are all functional plugins, for SEO and such, although I have not gone through each of their CSS sheets. That being said, I disabled all of them and the error during the speed test was still present.

The only place I did find a reference to header.png was in my old theme’s stylesheet, which was deactivated weeks ago when I replaced it with Genesis. I went ahead and deleted the whole theme in entirety in case it was somehow causing the request.

I have also cleared my cache.

I am using W3 Total Cache, but I have cleared it multiple times and the request is still made when I have it deactivated.

Where else should I look for the source of this dang request? Is it possible that my wordpress install is just f-ed up and needs a fresh install?

Thanks in advance for your direction!