LOL, my buddy had this same prob on his project...
He had gotten a 93 DX hatch shell and we put in a B16A2, he had the EXACT same problem, we couldn't figure it out for like 2 months...
Turns out it wasn't a vacuum hose leak, but the seal around the brake booster (large circular thing in front of driver side on firewall) was bad, causing air to get in and cause the crazy idle...
Some glue/caulking fixed it right up!
Hope this helps I know it took us a LONG time cause we thought it was an actual vac hose leaking...