Here's a thought...
I suggest you make sure that your battery terminals are clean and making a good connection. The best way to do this is to remove them and clean them with a wire brush tool made for the purpose, or one of the reaming tools. The other problems sound like they could be caused by a poor ground or grounds. Does your car have lots of rust? Make sure the engine to frame grounding strap is in good shape.
'82 300D/4.3L V6