My 03 impala makes a knocking noise when it is cold and goes away when warmed up,i have had people tell me it is the lifters but im not sure.Can anyone help?

 

Its the lifters goes away after a couple of seconds? Next oil change put in a bottle of Z Max should get a little better.

 

not sure how prone the impala engines are to this..
but on the inline 6 trailblazers - and some other engines- they get what is called Cold Carbon knock.
cold engine in the morning- the engine knocks a little. once its warmed up- its quiet.
This noise can be quieted for a bit- by running a bottle of chevron techron to get rid of the carbon buildup.
Mine quiets down a bit. not entirely, but it does help.
if you try chevron- and it doesnt quiet down- then at least you cleaned your injectors, and you then proceed to another cause.