2002 Ford Taurus engine pulses or shakes

Recently the engine light is on for one month and my car starts to shake abruptly when I stump on the brake and the car is stopped. When I set the transmission at back and drivie position, the car shakes (or jumps)one more time. A mechanic changed the engine filters (maybe) on the top of the engine and cleaned them, skaking is reduced and the engine light is on again after 1 week driving. I can feel the brake pedal trembling very fast rigiht now. Can you please tell me what is going on?

Thanks a lot.