thanks for the reply. the thing is it used to idle around 800 but just changed to low idle without any other indication. and its pretty lumpy in park (smooth with a slight shudder occasionally in drive). Changed all the 'usual' things like idle valve temp sensor ect thinking it was some kind of sensor failure. The duty cycle fluctuates around 50% at idle and 45% at 2500 rpm. the engine mounts are about a year old.