my new toy has had perisistent, yet intermintant idling probs. Sometimes its fine, but other days it shakes the whole drivetrain back and forth whilst sitting lights, whilst rising up and down in revs from 1000 to 800 and back again. It also decided to idles at 1300 rpm one time when warm which was odd - it did this on the same day it was snatching badly when letting off the throttle. It gets fed a diet of BP Ultimate only, from mostly from the same servo.
It also has a slight but not quite miss when accelerated gently off idle with no load on the motor, almost like a failing spark plug (they are new).
I am thinking vacuam leak, or dodgy idle control valve.


Any other ideas?