Recently my '01 5.4 has started idling up and down when it's cold. It's always idled up at ignition when cold for a few seconds as it should, then it comes down. What's happening now is it idles up and down as normal, then after about 3 seconds does the whole routine again. This will happen a few times until it has ran a minute or so then it is fine.

Only happens when it's below about 45 in the morning on a cold crank. Could it just be a dirty IAC?

 

or... a dirty throttle body or...TPS