Blue Buffalo all natural cat food, Science Digest, Petsmart brand sensitive stomach and another venison and pea recommended by the vet but I can't recall the name. I have tried duck, turkey, salmon, whole grains, brown rice, oat meal, etc etc.
Most recently I have been giving him Petsmart Brand (Authority) sensitive stomach turkey with digestive enzymes on top and that has SIGNIFICANTLY reduced his throwing up. In fact we went for a whole month with nothing. Then he started throwing up about once a week, but if he threw up once it would be several times after that and generally it is just bile, not whole food.
However, yesterday, he threw up whole food (so I thought he had eaten too quickly), but then he threw up about 7 more times after that within 2 hours. He stopped and I thought he was finished, but then he threw up 3 times in the middle of the night and a few more times this morning. He is now resting. He is happy, purring, seems to be using the littler box and has no other signs of being sick. In fact, he seems to be interesting in drinking water.
I would gladly take him back to the vet but after a $500 bill and all the tests you can imagine and all I got was he has a sensitive stomach, I dont want to drag him back there again. He does not do well in the car!