When I press the gas pedal, I can feel a delayed speed-up but not an immediate acceleration (I slightly press the pedal, I can hear and see an inceased engine rotation, and then a delayed acceleration.)

Anyone has ideas which part I need to check?

I just changed tranny oil, but I don't know that would be helpful.

 

is this in a automatic or manual? if automatic, a slight delay is normal.

 

EGR ports. Plugs n wires.

 

what is the EGR port?
I browsed some webs, some suggested to check vacuum lines. Any helps?
thanks in advance.