Rattles under hard pulling may be the result of a failed motor or transmission mount, or failed lower trailing arm bushings below the rear axle. Look first at the engine mount just below the oil filter on the passenger side of the engine. If the car seems to want to steer itself from the rear end as you drive down the road, the trailing arm bushings are shot.
I cannot explain the black smoke, however.
The best place to post Volvo 240 questions is in the Rear Wheel Drive (RWD) section of the Volvo Brickboard forum. That forum holds a gold mine of Volvo 240 knowledge.