Are you still using points or electronic ignition?
I have noticed one time my car pinging and after checking the points it ran 100% fine.
Was your timing always on 10 degrees or always on 7 degrees.
As I understand, you are also at the coast and not inland.

Correct me if I'm wrong but is'nt timing different for inland and cars at the coast?
I cannot imagine that it could have skipped a tooth. It will not idle properly then.
My uncle's volkswagen jetta was taken in for a timing belt replacement.
They replaced the belt for him. After coming home the car would'nt idle properly.
He discovered a tooth was skipped with the belt replacement. After putting it in the right way it was 100% fine.