Try increasing the curb idle screw adjustment. I set mine with a hot engine, turn it clockwise until the RPMs go above the 775 idle RPM then back it...
With engine swaps and a lot of EFI the throttle bodies should become more available and priced less. In the past you could find them for less $100. ...
Delorean was my dream car growing up and now I have 2. Trying to restore them the best I can. I live in MA and always looking for car shows to go to, to show them off. Keeping them as original as I can.