What is causing the car to jump when shifting from N to D? on 1990 Lexus LS400

I feel a sudden shock (jump) when I shift from N to D
This problem happens only when the car is stopped and I shift from N to D
This is not happening every time, sometimes the shifting from N to D is smooth
Otherwise. the transmission is shifting very smoothly between all gears at all times
Thanks for your help

Asked by for the 1990 Lexus LS400
1 answer 1 comment
this could be several issue from motor mounts to high idle, and poss trans issues.seek a diag at aamco for free to make sure trans is ok then move to poss other issues
Thanks for your help,
Idle speed is normal, no error codes for transmission but sometimes I hear a loud sound of "whistling" when starting the engine in the morning before engaging transmission, this sound goes away after sometimes
I think this sound coming from oil flow which is stuck somewhere in the transmission