I notice it only when Idling, the car / engine just vibrates and shakes the whole car. It does it regardless of weather the engine is cold or warm.

Also, I have problems starting the engine when its warm, It starts but revs at around 500rpm before dieing, I can give it a bit of gas it is completely fine after that.

No, I haven't fitted bosch plugs, they are NGK, should I have fitted bosch plugs?

Jason