huh, surely taking the EGR off a running engine would have some very noticable effect if things were not clogged. on the pre-93 intakes the EGR travels through a small passageway cast into the wall of the plenum and exits just behind & below the TB:

you can see how carboned up mine was after 100k. note the hump of the passageway going to the EGR mount.

there is also a 19mm plug bolt right next to the EGR - pulling that makes it easier to inspect/clean that end of the path, while obviously pulling the TB is the only way to check out the exit end.

although I don't think that would explain a low idle. when you manually depress the EGR, it stumbles/stalls because you are opening the loop & pulling in exhaust at low rpm, correct? so a really low idle, if EGR related, would point to the valve(and path) always being open.