EGR cooling?

Having trouble passing smog (high NOx) on a carbed pickup that uses EGR. I already cleaned the EGR system and there is no more charcoal in it. I need more EGR or cooler EGR as I milled the head a little more than recommended. Would it make a lick of difference if I ran my EGR through a trans cooler? sort of an Air to air cooler? would it make more sense to just get a larger EGR valve (or hog mine out at the pintle hole) the EGR uses a pretty small opening (maybe 4mm) and a cone seal. diesels have water to air coolers but I have an extra finned trans cooler.