Steve you are SOL you have a "smart" EGR system
In interim easiest thing for you to do is put shim under the EGR.
That way when it is opened by vac it can't physically flow EGR gook, but it keeps the PCM happy because it is looking for change to the vac system when EGR is commanded to open, PCM does not monitor EGR, it monitors vac applied or vented to/from the EGR valve & EGR solenoids