Fuel pump relay
I had a similar problem, with my 500SEC.
I soldered the connection and it broke again.
It is important to bring up the heat in the joint
before you apply the solder. Otherwise, you are doing just what the factory did.
I did find a newer relay in a junkyard but it did the same thing.
I fixed them both and carry a spare in the glove box. So far, I haven't needed the second one. Going on 15 months.
I understand that new ones are $154.
Good luck, JF