Has anyone ever choked to death while eating peanut butter?

Certainly. Many persons are Allergic to Peanuts.
I imagine that someone HAS choked from simply not being able to swallow a large wad of PB as well.

"Why Does the Body Go Nuts Over Nuts?

When someone has a food allergy, his or her body sort of misfires. Instead of treating a nut or peanut like any old food, the body reacts as if the nut or peanut is harmful. In an attempt to protect the body, the immune system produces antibodies (special chemicals designed to fight infections) against that food.

The antibodies then cause mast cells (which are a type of immune system cell in the body) to release chemicals into the bloodstream, one of which is histamine. The histamine then causes symptoms in a person's eyes, nose, throat, lungs, skin, or gastrointestinal tract.

In the most serious cases, a nut or peanut allergy can cause anaphylaxis."

http://www.kidshealth.org/kid/health_problems/allergiesimmune/nut_allergy.html

"The most common specified food objects that victims
choked on were undetermined meat products (17%), and of those characterized, steak (10%) and chicken (5%) were the most highly represented.

The next most common food object was a peanut butter and jelly sandwich (4%)...."


http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1556-4029.2006.00297.x?cookieSet=1

Maybe not choked to death, but I suspect that people, unknowingly, with severe peanut allergies that ate peanut butter would suffer anaphalactic shock, where their throat would close up, and they would pass out and die.