started the x this morning and when engine went to normal idle the engine made a noise that sounded like a diesel engine noise..you know that noise a diesel engine makes when it idles..like a piston noise...it did not sound like a valve noise..more like a piston slap noise..it did it for literally a few secondsthen it went away..it sounded like it was coming from the drivers side bank...i have the 4.4....you can also describe the noise like when the bearing goes bad in the water pump...but i dont think it could be that because i just had the pump changed 3 weeks ago...it only happens when the engine is cold....do you think anything to worry about....2005 x 4.4 with 18k miles..thanks rob