Hi Siddiq, The problem you are having with your Pajero has nothing to with any gasket. The low idling speed that causes the vibration happens because the step-up actuator does not work. The device works on the trottle, and it increases the idling speed when you put a vehicle in gear. When you put an automatic vehicle in gear, the transmission engages, which reduces the idling speed due to the drag of the transmission, so the transmission sends a signal to the step-up actuator to say that it is now in gear, and it must increase the idling speed to counter-act the drag the transmision places on the engine. When you drive at higher speeds, the engine overcomes the drag of the transmission, which is why you don't notice the vibration at high engine speeds. Remember that N and P is not the same thing, because different parts of the transmission is disengaged in N and P. When the transmission is in P, the fluid in the transmission follows a different route through the transmission that causes less drag than when the transmission is in N, so you will notice a difference in how the engine idles when it is cold, and in P. The step-up actuator also works on a signal from the AC, so it is possible that the circuit from the transmission to the actuator does not work, while the circuit from the AC compressor might work, which is why you don't get the slow idling and vibration when you turn on the AC. I suggest that you take the vehicle for a full OBD II diagnostic check to confirm that the circuit from the transmission to the step-up actuator is defective. It is very difficult to test this circuit yourself, since you don't know what the electrical values on the testing points should be. There might be some power in the circuit, but a high resistance because of bad connections, or a defective switch, so have this circuit checked out with a diagnostic computer.