2003 Ford Focus 2003 Ford Focus Clacking/Tapping noise...th

for about a week everytime I crank the car up in the morning there is a loud clacking/tapping noise..when I rev the motor it gets even louder..almost like when you need oil...My husband checked oil and all fluids and they are good. The oil was just changes about 6 weeks ago. The funny thing is once I run the car so for a couple of blocks the sound idles out and fades away. The noise is only in the morning when car is cold, at crank up, drive and idle all until the temp gauge moves to normal, then its gone. Lifters? Piston Slap? I've heard a couple of things...just need more opinions? Thanks