Heres my history. I installed a blocker plate in my truck several months ago, did not install the finger stick. Truck ran fine and did not get service light. Truck recently has miss like or shake when in park, so I removed my blocker plate, to bring truck to dealer. Oil poured out when I opened the flange to remove blocker plate. Dealer said I had code 401 & 403 and replaced egr. I never had a service light come on, or these internal codes? Caused by blocker plate? What they did, did not fix the miss like symptom when in park. Debating whether to reinstall blocker plate and finger stick or just leave out. Do I have to reroute PCV to eliminate the oil build up behind the plate?

Yes, reroute will eliminate the oil but if they didn't fix it I wouldn't reroute or put the plate back in just yet. Did they do the work under warranty? Take it back and show them it's still idling rough. It may be something else causing the porblem.

Yes they did the work under warranty. I'm planning on leaving it out, at least till I get the rough idle fixed.