Hi, Actually I changed spark plugs along with its 6 spark plug gaskets and both the head gas kit (from Top). The vibration was there before the gasket changed and at the time of purchase. Apart from that the car is in excellent condition when it comes to interior ,exterior and engine performance. Below are the RPM reading noted after driving 40 kms. P : 800 (without AC) N : 800 (without AC)D: 500-800 (Without AC) I can feel the vibration in all the above 3 states.