I pulled my codes, now I have a question?

Me and my friend, 94YellowStang, pulled my codes a few days ago. The only code that we got was 33. Our book states that this has to do with the EGR valve not opening or not closing properly. :notnice: I was wondering if any of you all had dealt with this problem and if it was as simple as replacing the EGR valve. :shrug: Can this EGR valve problem affect WOT performance or cause pinging. Thanks in Advance!