HI EVERYONE

Let me start by saying Happy Holidays and Prosperity for all in the New Year.

I'm having this rattle sound coming from my engine that the dealer seems to never hear. I've taken it in about 3 times for this and they keep saying that the car is operating fine. I'm familiar with the rough idle of this car and the little valve clatter here and there signature of this engine.

However when i come to a stop at a light and the car is idling it starts a tuck tuck tuck tuck sound audible from the interior of the car enough to be heard by my passenger. It also does it when you are in neutral and blip the accelerator to about 3,500 rpm and quickly let go of the gas it will idle down making the same noise for about 2 seconds.

I dont know what it is but i have a feeling the its valve related. Any suggestions or similarities?????