EGR valve was Duralast. I was thinking that it could be a vacuum leak however this vehicle only uses a MAP sensor and not a MAF sensor so a vacuum leak should be accounted for since it is calculating fuel based on intake vacuum versus air flow. Is that correct line of thinking or no? As far as identifying a leak I wasn't able to do that which is why I went ahead and just replaced the EGR valve. MAP pressure reading is about 4PSI when the issue is occurring which looks like a good reading. Any suggestion on verifying EGR valve function?