1980 250 info?

Well first.. I'm new to Mercedes and I'm new to this BB.. I'm really glad I found it though.. I have a lot of questions
I recently bought a 1980 250. It has about 134K, and the body and interior are in great condition.
Trying to insure the car.. my insurance company says they dont have any record of a 1980 250. So we made it a 280C
Then Ive noticed just from trying to buy tune up parts that no general auto parts store has this car either.
So I'm wondering.. is this car pretty rare? any idea how many were produced?
My next question is.. why does it stall whenever the slightest bit of gas is applied after a stop? And what is the normal engine operating temp? The previous owner said this was an "english edition", just wondering what that exactly is?
Thanks for any help or advice!
Heather