wp_insert_post bulk import 500 server error

I am working on a WordPress import tool, where I use a custom city table in my database with longitude, latitude which combine with some other text and then import by wp_insert_post(). This works great but after 3200 – 3600 the script stops and I get a 500 internal server error.

I have tried multiple solutions to fix this problem:

I increased the following php.ini settings:

• max_input_time
• max_execution_time
• memory_limit
• mysql.connect_timeout
• max_input_time
• post_max_size

Increased the WP_MEMORY_LIMIT is wp_config.php:

define('WP_MEMORY_LIMIT', '128M');

And increased my time limit in wp_config.php too.

set_time_limit(240);

Tried it also with my htaccess file:

php_value max_execution_time 240

Debugged my bugs but I still got the 500 error.

I contacted my host and they told me to set the set_time_limit(); which I have set in function.php, in the file of my importer and wp_config.php, but no success.

I viewed my php settings by phpinfo(); and there I have a max_execution_time of 120. I have asked my host to increase it and still the same problem.

This is my import script:

// Get results
        global $wpdb;
        $results = $wpdb->get_results( "SELECT * FROM stn_locations" );

    if( $results ) {

        // Submit button clicked
        if( isset( $_POST['submit'] ) ) {

            foreach( $results as $result ) {

                // Set variables
                $location_name      = $result->stnl_name;
                $location_longitude     = $result->stnl_longitude;
                $location_latitude  = $result->stnl_latitude;
                $location_country       = $result->stnl_country;
                $location_term      = $_POST['term'];

                // Content
                $location_content       = $_POST['stn_filter_import_content'];
                $location_content       = str_replace( '%%location%%', $location_name, $location_content );
                $location_content       = str_replace( '%%category%%', $location_term, $location_content );

                // Build post_title
                $post_title = $location_term . ' ' . $location_name;

                if( $location_country == $_POST['country'] ) {

                    // Import data
                    $import_data = array(
                        'post_title'    => $post_title,
                        'post_content'  => $location_content,
                        'post_status'   => 'publish',
                        'post_type' => 'filter',
                    ); 

                    // Insert post
                    $post_id = wp_insert_post( $import_data );

                    if( ! is_wp_error( $post_id ) ) {

                        // Set Term
                        wp_set_object_terms( $post_id, $location_term, 'service' );

                        // Set meta fields
                        update_post_meta( $post_id, 'longitude', $location_longitude );
                        update_post_meta( $post_id, 'latitude', $location_latitude );

                        $success = true;

                    } else {
                        $error = true;  
                    }


                }

            }

            }
}

Does anyone have a solution, tip, setting or other function for me? Let me know! Thank you.