Update: It turned out to be various PHP Errors when creating the PDO Objects. This may seem obvious, but using a PHP Log file is really important in this framework for debugging. I setup the PHP Log file with the following commands in my Quickbooks Config file qb_config.php:
ini_set('log_errors', TRUE); // Turn Error logging on ini_set('error_log', 'php_errors.log'); // Logging file location ini_set('log_errors_max_len', 1024); // Optional Log file size
Once logging is setup, all PHP Errors that may cause Web Connector errors will be displayed. I also wrote to the log using error_log('Some Text',0) to help debug the code.