Noisy on start up l322

Hi All, i have had a few problems with my 2003 4.4 petrol and have just replaced all the timing chains ect. I did have a few problems when starting the car from cold but I have more or less solved this.However when it starts from cold and and I put my ear to the air filter casing (dont ask) I get a rough noise coming from it and it’s not the sound of air I don’t think then after minute or so the car starts to run smooth and I hear a popping noise and the noise goes away. I have had a smoke test done and all seems ok any ideas lads or lasses.