2002 Jeep Cherokee Laredo stalls while driving

My daughters Jeep stalls while driving and
sometimes while stopping at lights, sometimes it
starts back up and sometimes it takes awhile.  Took
it to have computer hooked up for codes but since
there is no check engine lights on the dash they tell
me it won’t show anything.  So we started just
replacing some common things people suggested
like idle control valve, throttle positioning sensor,
fuel filter, higher octane fuel with fuel treatment and
still the same problems.  What should I try next?
Thanks in advance