My check engine light comes on and off at times. I got auto zone to hook up

insufficient egr flow.take the egr valve off,clean it,probably clogged with carbon,in bottom.possible dpfe sensor is bad.if yours is metal,it is from factory most likely.the redesigned one is plastic.now,you can take this with a grain of salt.cause you will get mixed reviews on what i gonna say.if this has not been done,it needs to be.remove the throttle body,carefully.turn it over and look at the 2 egr passages on the throttle body.ima betting they are clogged up so bad,that you wont believe how bad it is.but,i want you to google your code and on ford forums site,look at the pics.of the throttle body,before cleaning,and after.then reply back.there are step by step instructions on the site.look for it,you will see.i think the pics. are from greg upton.its not hard to do.