88 D100 issues

Unplug the Idle air control so it quits trying to communicate with the computer. Disconnect your battery for 60 seconds to clear the computer codes and reset it.

Set your idle manually. Or remove the IAC all together and build a steel bracket with a 1/4" bolt to replace the plunger and set idle manually permanently.

One and Done.

Go easy on your liver, no fun being outsmarted by lame electronic systems. Go with the manual work-around and get back to enjoying life.