I was plagued with stitch/cramp almost every run for more than a year to begin with, running evenings after work, found more or less exactly Filberts method too by trial and error - works pretty well - frantic drinking in the last hour before my run because I'd forgotten earlier made it worse.
I never get a problem in an early morning or mid-morning run. I don't have loads of energy early in the morning but I like that empty, light feel.
I try to avoid bread for lunch on running days, found this by accident, it seems to help I do have a pretty "windy tummy"(!) so try to avoid all the things I know will make it worse! Rules out pretty much everything for me except porridge!!
Also trying to do a 2:3 breathing as much as poss,helps too I found this difficult at first, but now it's automatic, I was always doing 2:2 (probably always in and out on th same foot).
I discovered by accident in winter, tying my top tightly round my waist quite high up, I thought this was because it stopped me gasping for breath too much, but then I read an article about your insides joggling about, so perhaps this helps stop that!! Feels comforting too.
Now I run more regularly I don't have such a problem, but if I lay off or cut down for whatever reason it seems worse when I try to do more.
Hope some of this might help.