thanks Bluetec I'll try to do that, yeah the vibration its more noticible at idle, when the car is parked its fine but also if I go on the back I can hear my exhaust noisy like if the noise was coming from front to the exhaust, I don't know if that makes sense, also sometimes when I start the car and put it on gear fast, it shakes a little bit, so I was thinking something to do with the spark plugs as you mentioned..