I nabbed a junkyard idle-up adjuster from an '83 Caddy Seville yesterday... there was a similar one on an '86 RWD luxo-barge. This is the electric VARIABLE actuator, not the one-setting electric actuator (or its vacuum brother). It has a snazzy bracket that should be easy to adapt...
4-wheelers actually use these to idel up or down incrementally -- for CTD use, you may want to set the extreme 'up-travel' to be the desired fast idle...
Pictures to follow.
Randii