He has owned numerous Mercedes diesels including a couple of 240s that he has repaired and is fairly knowledgeable. I don't know the particulars on acceleration time but as he describes it I'm reminded of my 82 300D with numerous vacuum issues. You almost can't get it going forward on an incline without a running start.

This car had been sitting for several years when he bought it to restore it. Linkage was stiff, fluids were old, fuel was bad. He's changed fluids / fuel / filters, run cleaner through the fuel filter, purged the fuel lines, lubricated linkages, etc. It starts almost instantly and runs smoothly at idle, even when cold. Initially it would barely do 40 MPH and crawl up to that speed. Now it cruises comfortably at highway speed when it finally gets there but it's dangerous trying to accelerate to that speed in any kind of traffic.