We had problems with formula feedings as well. We used Jevity 1.2, and we were also giving my mom the maximum amount of Imodium every day. The diarrhea continued, and our doctor finally wrote a prescription for Paragoric, which is a controlled substance that can help with severe diarrhea.
I gave her one dose of Paragoric after we received it, but I also started giving her baby food instead of the formula. Then I started experimenting with puréed food recipes--just making up my own concoctions--and the diarrhea stopped. We haven't opened the bottle of Paragoric since that first dose.
You will battle nutritionists and nurses if you make your own food, but here is the argument that I use. Everything was running right through my mom when she was on the formula feedings, so she wasn't getting the nutritional content that she needed. Plus, she had problems with residual, so we couldn't give her the prescribed amount of formula each day. Now she digests her food, her stools are normal, and her skin looks amazing.
Here is a sample of what I make for her: 2 cups of almond milk, 1 can of Mandarin oranges (lots of vitamin C), 1 can of puréed sweet potato (dense calories), half a can of puréed tomato, 1 cup of oats, 3 tablespoons of flaxseed (omega-3's plus lots of calories), 2 tea bags of green tea, 1 tablespoon of garlic (antioxidant), 1 teaspoon of cinnamon, and 1 teaspoon of turmeric (these last two were recommended by a doctor to combat MRSA--I have since then read about turmeric's benefits in a Vegetarian Times article). Purée this in a blender, adding ingredients a little at a time, and then store it in the refrigerator. Mix it with V-8 juice or another vegetable/fruit juice to get a good consistency for the tube. You can put it in the tube with a syringe and plunger--use the plunger to suction the food up into the syringe, then push it into the tube. Be sure to flush with water before and after, and try to get a good "burp" to avoid gas problems. In addition to this food formula (which varies somewhat--if I have a ripe banana, I'll use it, or whatever other fresh produce needs to be used quickly), we use a vegetable-based protein formula at night, mixed with 2 cups of carrot or other juice. This helps increase her calorie intake. You can find protein mixes at health food stores and large grocery stores. You can also get them online, of course.
Disclaimer: I am not a nutritionist, so I am giving this information only to share what works for my mom. Baby food also works, but this can get expensive. We still use baby food when we have run out of the puréed food and I don't have time to make more right away. I estimate that she gets around 1600 calories a day, which is far more than she was getting with the Jevity.
Oh, we also give her two containers of DanActive yogurt in the morning, mixed with cranberry juice. Our doctor recommended the yogurt with active cultures to help balance out the GI tract. This might be a good way to start experimenting with things other than formula feedings if you aren't keen on puréeing everything just yet.