I had LIS 5 weeks ago and before that also suffered from chronic diarrhea for two years. I had tried everything (I thought), including fiber changes in my diet, eliminating certain food groups (dairy, lactose), 4 VERY expensive probiotics, but nothing helped.
After LIS though, I stopped drinking coffee (because to me, it was always what I enjoyed while sitting at my computer first thing in the morning, and lying on the couch seemed more like a tea "thing"), and started having two cups of tea every day instead. I have no idea if or how this change could be related, but I have not had one episode of diarrhea since then.
I'm posting this now, in case someone else suffering from diarrhea may experience a similar effect if they change from coffee to tea!