EGR PROBLEM

I have a 2002 Ford Taurus, with approximately 60,000 miles on it. A light came on, and when checked it said too much EGR, so I replaced the EGR. The light was off for a day, then came back on. The mechanic said maybe it was the EGR sensor. Does this sound right? If I do not warm the car up before driving, it tends to hesitate for awhile, until it does get warmed up. Is there something else that would be causing this?

Thanks,

M. Cole 8)