I do not think this is the answer. I have not got PHx installed
This is the answer. But you are not obliged to follow my advices

AjaxSearch uses internaly the same functions as Phx. Even without Phx installed, you use the same functions (Extended placeholders & parser).
The instructions are not very clear. I am a modx newbie so this is all a bit new to me.
I understand. This subject is tricky.
A/ To avoid to display the results you shoud specify &ajaxSearch=`0` and specify a landing page with the &AS_landing parameter
B/ Regarding the broken parsed placeholders, this issue comes from the limitation due to the pcre_backtrack limit PHP parameter. This limitation will be bypassed with the next release of ajaxSearch (1.8.5). This release will be provided
with MODx 1.0.3. Waiting this new AjaxSearch release you could install the fix on your current 1.8.4 release. For this do as below:
open the file assets/snippets/ajaxSearch/snippet.ajaxSearch.txt
1/ Replace the lines 68-69:
//include snippet file
define ('AS_PATH', $modx->config['base_path'].AS_SPATH);by the lines:
// include snippet file
define ('AS_PATH', $modx->config['base_path'].AS_SPATH);
// pcre backtracktrack limit
define ('PCRE_BACKTRACK_LIMIT', 1600000);This defines a value for a constant named PCRE_BACKTRACK_LIMIT.
2/ then replace the lines 412-414:
$as = new ajaxSearch(AS_VERSION,$cfg,$dcfg);
//Process ajaxSearch
$output = $as->run();
by the following lines:
$as = new ajaxSearch(AS_VERSION,$cfg,$dcfg);
//Process ajaxSearch
$current_pcre_backtrack = ini_get('pcre.backtrack_limit');
ini_set( 'pcre.backtrack_limit', PCRE_BACKTRACK_LIMIT);
$output = $as->run();
ini_set( 'pcre.backtrack_limit', $current_pcre_backtrack);With these new code lines, you save the current value of the PHP pcre.backtrack_limit parameter. Then you increase the current value of this parameter, execute the search and then restore the pcre.backtrack_limit parameter.
Any more guidance help would be appreciated.
Hope this help suit your request.