How about grabbing the response text in one variable, then splitting that variable up into bits and then putting those bits into their respective text box.
The response text would've been something like:
var someString = pageRequest.responseText;
var temp = someString.split(',');
text1.value = temp;
text2.value = temp;
text3.value = temp;
text4.value = temp;
Assuming you're using PHP you could use the implode function to add those strings together.
http://php.net/implode <-- Implode reference