Boy, you really do sound just like me. I gave up so many foods trying to figure what could possibly be a culprit. I recently discovered that chocolate is not my friend - much as I hate to admit it. :-( But now that I'm not eating it, I'm doing even better.
For my IBS symptoms, I follow everything on the website I posted earlier: www.helpforibs.com
I don't take the supplements they recommened, because (oddly enough) my IBS isn't all that bad. I definitely do follow all the information about eating soluble/insoluble fiber. Take the time to read up on all that stuff. I even copied and pasted a lot of the info into a Word document, so I could print it and keep it as handy reference. The website author created a cheat sheet that you can stick on your fridge, too.
Now, aside from the IBS stuff, I did the spinach/sunflower diet but only in the form sunflower butter and cooked spinach. Do not eat the seeds and do not eat fresh (raw) spinach - they will tear up your gut for sure.
To take it a step further, I apply the soluble fiber guidelines when I eat my spinach/sunflowers. In the morning, I toast a piece of white bread (bakery stuff, not Wonder or any of that garbage) and put on lots of sunflower butter. Sometimes I top it with sliced banana, because it's so yummy together. In the beginning, you may want to repeat this meal later - maybe as your afternoon snack or something. Just be sure you eat at least a few tablespoons of sunflower butter every day.
Then for the spinach, I eat cooked spinach either with white pasta or with peeled, cooked potatoes. The pasta and potatoes creates a buffer, making the spinach easier for you to digest with your IBS. I probably ate 1/2 cup of cooked spinach every day in the beginning (I'm a fairly slender female, so depending on your size/sex you may want to eat more or less).
One note about eating spinach - tempting as it may be to eat it with cheese, try to keep cheese to a minimum. The calcium in it cancels out the magnesium in the spinach.
I don't know how much you've already read about the spinach/sunflower diet, but the whole point is to eat lots of beta carotene and magnesium. For some reason they improve symtoms. Sunflower seeds also contain another nutrient that I can't remember, so it's important not to substitute with other foods, at least not in the beginning.
Once you're in remission, you can start trying out other foods that are high in these nutrients, but wait until then.
Whew, that's a lot of info, and I hope I haven't left anything out. I think I covered all of it, but if I remember anything else I'll post more.
Please do ask any questions you have about it. It has completely changed my life, and I hope it works for you, too. 
DX: Pancolitis as of 9/08 (Proctitis as of 1/08) and IBS
Current Treament: Spinach/Sunflower Seed Diet
Previous Treatment: Canasa suppositories, Cortifoam, Prednisone, Colazal, Symex DuoTabs, Rowasa, Bentyl, Cortenema, Asacol, Iron, Zoloft, Acidophilus.
Status: Remission