Typical of a dirty MAF (Mass Air Flow) sensor.

Will also sometimes show as hesitation on acceleration.

Instructions for cleaning are on many ford sites..

But they are typically mis-informed like This guy:
http://www.fordf150.net/howto/clean-maf-mass-airflow-sensor.php

I use rubbing alcohol and a new small paint brush..  though you may
follow his directions if it makes you feel better.

If you wonder who is right... he is 'Dan the Oil Man' I am BM the former
electronics engineer,

Disregard
http://autorepair.about.com/library/faqs/bl827d.htm

as they simply parrot Ford position on it.