nissan elgrand 3.2 ltr auto diesel 1997 idel speed ?

my elgarnd will idle at 600 rpm = in drive +a/c on and turing the steering wheel left + right no drop in power or vibration . a frend of mine has just bought a 3.2 elgrand auto =idle speed is 1,000 rpm and is vibrating quite bad when at idle, the seller (garage) was told to reduce the idle = idle set at 800 rpm. now in drive at idle (brake on) and turn steering wheel left+right = no drop idle speed but the vibration is so bad the hole car from front to back is vibrating ? to all elgrand owners with 3.2 autos just WHAT IS YOUR IDLE SPEED IN DRIVE ,IS ANY THING VIBRATING ***HELP***