Common prob with the '02's. I saw a thread the other day where a guy mentioned the dealer replaced his alternator for sending some incorrect voltage back to the PCM, and it fixed his prob.
I have had the same problem since it was new and the dealer told me it was normal for these cars. Mine is an 03' and I have replaced the IAC and it didn't fix it. If you go to the dealer and the Alt. fixes it....post back up and let me know if it fixes it. I would love to know!
i had a ford tech that worked for them for 40yrs tell me that its a common problem in these cars and to first let the fuel system get primed up then start it but it is no garantee that it will work all the time there will still be a once in a while long start up