Is it permissible for someone who suffers from intermittent and irregular flatulence, which causes a loss of concentration (khushu') and necessitates repeating prayers, to adopt the ruling of سلس (perpetual ritual impurity), knowing that it sometimes stops for a period long enough to pray and sometimes occurs during prayer?

If your feeling of passing wind is merely an illusion or a doubt, then do not pay attention to it. However, if you are certain that it has occurred, then if you know that it stops at a specific time sufficient for purification and prayer, then wait. But if its cessation is erratic and irregular, then your ruling is that of one afflicted with perpetual discharge (sahib al-salas); you perform ablution after the entry of the prayer time and pray whatever you wish until the time for that prayer expires.