Long story short, I've been attempting to upgrade from 1.3.9 to 1.5.4. After trying the traditional route of upgrade, I decided a clean install actually made more sense and would probably be simpler, considering I want to totally revamp my store anyway. Easier said than done, of course.

I installed a clean version of 1.5.4 in a subdirectory for testing
I created a new DB for the test install and imported my current DB into it
I ran zc_install.
My admin panel works. My shop does not:

http://smarmyclothes.com/testclean/

The error in the debug logs is:
Code:
PHP Fatal error:  Class 'QueryCache' not found in /home/smarmy8/public_html/testclean/includes/autoload_func.php on line 79
I searched and found this thread:
https://www.zen-cart.com/showthread....ad_func-php%29

I followed the suggestions: re-uploaded /includes/classes/query_cache.php and /includes/autoload_func.php several times.
I even deleted them and uploaded fresh, just to make sure. But the problem (and the debug error) persists.

Any help is greatly appreciated, because I am lost.