EGR valve - PO removed and plugged vac line

[TimQ]

I've been tinkering with my truck (86, c10, 4.3 v6 with 92k miles) for the last year I've been slowly working on one problem and then the next. Good news is, after some problems with stalls, cracked flex plate, and some other stuff, she's running as good as ever since I've owned her.

When recently tracking down a vacuum leak to an old and cracking hose, I noticed that the previous owner had disconnected the vac line from the EGR valve and plugged it (plugged the hose not the port on the EGR valve). It's been like this, I assume, for the 15 years I've owned it. When I hooked the line back up, the truck idled rough and stalled out (never left the driveway) so I just disconnected it again, plugged the line, and left it be.

I'd like to see if I could get it hooked back up properly for both the mileage and emissions benefit it is meant to give. I already have a new EGR valve and was going to try to install it this weekend. Any tips on what adjustments I might need to make once I hook up the new one? Does it sound like the existing one is faulty? Any thoughts are welcome.

Thanks,
TimQ