@chinasvegas
Yes have had this condition for a long time.
Have you been tested for allergies? They can cause tremendous increase in saliva and of course running down your throat and getting into windpipe. I take an allergy pill once a day.

Food triggers can also "trigger" severe salvia response and the condition you describe as I get that also. Anything really spicy will have me coughing within seconds.

I would try to speak to your doctors about doing allergy tests to see if the amount of saliva and mucus being triggered can be reduced. Also keep a journal on food. The journal can help you find which food are triggers and the choking on salvia. I know a lot of work, but I was coughing really bad and the choking on salvia. I had to find remedies.

The mucus will go down your throat. Most of the time the body will move to the stomach as you swallow but can (like mine and yours), make its way to your airways and then the coughing reflect will be dramatic.

I see someone mentioned reflux. This can cause a real sensitivity in the throat area. Then eating and drinking, even coughing can cause tremendous mucus. It is why we need to find out what is triggering the mucus.

I try to avoid known triggers. What I found too was when I feel sensitivity in my throat I try to drink something that soothes my throat. That helps me also. But we are all different and what my triggers are may not be what is causing your symptoms so best to get it checked out.
Allergies can come at any time in your life. You can develop them at any time. I have become extremely sensitive to pine. Guess where I live, Florida. Half the trees are pine.
Good luck.