Choking While Eating

My cat Toby has had difficulty swallowing for about a year now. We took him to a vet and they seemed to think it was related to his teeth which were rotted, so they removed all of his teeth except for one (to make sure his tongue wouldn't stick out). His teeth have been removed for quite some time now but his breath still smells horrible and he constantly chokes on his food. We try to make his food as liquid  as possible by smashing up his wet food with lots of water, but he still sometimes chokes on that and runs away. We presume he is choking on small bits of food that haven't been properly smashed, but we're not sure. Occasionally he will even start choking when hes just sitting around. When he "chokes" he keeps his mouth wide open and sort of wretches. Although it looks like a choke, we're not entirely sure it is. What could be causing this? Also, I'm not sure if it's relevant but Toby has lost the ability to meow for a while now. Toby is very old and we want to make sure his condition warrants a visit to the vet. Thank you!