A.C.
Some cats are pukers, lol! My mom had a cat that threw up every day for the 21 years he lived. She had every test done, tried many different foods, hairball meds, you name it, she tried it. She finally just resigned her self to cleaning it up daily. She loved him enough it didn't matter, I guess. You may just have to accept it. Try tweaking his eating schedule and see if you can get him on a different "puking schedule." :)