You didn't mention where Firefox was being installed.
I assume /home/jdrake/Firefox.
Saveconfig does not do well at saving directories in your home.
I have always had a problem making anything persist
that was not in the Desktop directory. After many attempts
I finally had to install Firefox and Thunderbird in the Desktop
directory. If you show the Desktop icons it will become cluttered
quickly. Since I don't show Desktop icons that is no problem
for me.

Try installing Firefox in the Desktop and see if that works.