My cat is not chewing her food?

My cat was a stray before i got her a couple years ago and she wont chew her food. I have taken her to the vet many times already and there's nothing physically wrong with her. She vomits maybe 4 or 5 times a week and its made up of the unchewed food she just ate. Its not a hairball problem and its not her teeth or gums. the vet told me its most likely she is still in competition mode from when she was a stray, but had no suggestions for how to get her to start chewing her food. Any thoughts or suggestions?