How do you know that the EGR is working? Open the EGR at idle. the engine should run rough or stall. If not, you have clogged passages. Check engine temperature and carbon build-up. Be sure the correct heat range spark plugs are installed. Most of Nox has to be controlled at the engine. The reduction bed of the catalytic converor is limited as far as NOX conversion.
Conner

Over the hill but still climbing.
88 Montero 2.6L auto, manual hubs, cooling fan conversion gps,recurved distributor,LSD Diff.