When you are having a flare up your diet should be liquid. Once that has passed introduce thick liquids. There is a book ‘Living ( well!) with Gastroparesis by Crystal Zaborowski CHC. My book was published in 2011 so I’m sure there are later ones.
You should eat 6 small meals/day. When eating chew well until food is mashed potato consistency. Avoid a lot of fiber,spicey foods, foods that can cause ‘gas’ and many fresh vegetables.Once in the chronic stage you can try different foods to find the ones you can tolerate. No two people are alike. Carbs. are my best friend but I still have to watch the fiber. Oatmeal is good for you but it has a lot of fiber.
I was diagnosed after many emergency room visits and stays in the hospital with many tests in 2014. I still have ups and downs.
I hope I have helped you.