I'd follow what Christuna has noted.

Our local dealership supplies MB plugs alleged suitable but they are no longer resistor types

Next. Beru Leads a'int what they used to be.

Check the connections at the fuel pump for corrosion. In fact check every electrical connection you can find. Even go to the trouble of changing all your fuses. Any aluminum ones change them out.

Good luck with that car. It's a shame a rare EZL can render it down.