Range Rover Mark II / P38
I've got a 2000 P38 4.6 (Bosch) with about 120K miles on it.
Ordinarily, it seems to idle somewhere between 700-900. However, at stop lights recently, I've noticed an occasional 'dip' in the idle to about 400. It sounds like the car is about to stall (but so far, has always recovered)...