On my gastroenterologist's advice I take a tablespoon of Metamucil mixed in a half cup water (less water than the label on the container says) every morning after breakfast. He said the fiber helps "bulk up" the output. I find it helpful and it might be worth trying for those having a lot of problems.
I agree that the same food can cause different reactions - I guess not having the large intestine means your small intestines carry the burden and seem to be very sensitive - it's just a fact of life for us. I don't regularly take immodium (loperamide) but I do take it when the looseness etc. is just too much. Peanut butter is also good to slow things down. The main thing that helps me is eating simple foods like rice and beans, chicken, non-rough vegetables like cucumber, squash and so on.