Got Shell 93 Octane and now barely idles 1973 Dart 340

No need to drop the tank for water in the fuel, if you suspect that put a bottle of isopropyl alcohol in it. Sounds like a vacuum leak to me, where is it leaking? I would do like mentioned above, disconnect and plug all the vacuum lines, see if it still acts the same. Very likely that adapter is leaking if it has rtv on it.