My '89 300E was running great, all of a sudden it started blowing black smoke, low vacuum and the fuel range dropped in half.

I took it to a mechanic who swore it was ignition related and he replaced all the plugs, wires, and other ignition components. When I got it back, it ran exactly the same. When I returned it, he said it now needed a catalytic converter, Ox sensor, fuel pressure regulator, and fuel distributor. And he wanted about $4,000 to do the work.

I'm not convinced he knows what he is talking about, so I wanted to check here first. Does this sound right?

When I disconnect the wire on the EHA, it runs a lot better, less smoke and better mileage, but there is still some black smoke and I don't get anywhere near the mileage I used to get.

I appreciate any responses.
Phil