That's because they don't go in /cache. In your case they would go here:
C:\Program Files (x86)\Steam\steamapps\common\Saints Row IV\
Having the same problem with this mission, even after I've downloaded the patch and turned my graphics all the way down (it runs smooth but it doesn't look pretty).
I downloaded your files and extracted them to the above location on my hard drive, and still nothing.
Any help would be greatly appreciated, this small problem is ruining an otherwise very enjoyable experience!