car shuddering on deceleration and acceleration

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2007 Nissan Sentra 2.0 manual. I just replaced the plugs, boots (between the plug and the coil) and one coil due to a misfire on one cylinder. At that time the car was shuddering badly under load. That problem has gone away, but now there is different shudder. Hard to explain, but I will try. As I slow down the car will seem to coast for moment, but then it seems to grab the gear kind of hard, causing a jerking of the car. At the same time, if I hit the accelerator while coasting, it does kind on the same thing when grabbing the gear. If I'm driving kind of slow at a moderate rpm the car will shudder,or jerk back and forth, alternating between jerking when the gear grabs while slowing down and jerking when the gear grabs accelerating.