I used the Bentley Book to do it. I have never even messed with the little diagnostic thing on strut tower (driver's side). Worked like a charm. I plugged into terminal 2 and did what the book said (pushed the little button thing) and the injectors started cycling....after that, the IAC valve started cycling. Pretty cool. That was pretty cool.

Anyhoo...still wondering why the thing "limps" when you crank it up instead of roaring to life like the other 240s. I'll try the other diagnostics later...maybe the air conditioning ON relay ...or perhaps the throttle sensor??

Maybe it's just the way the '89 is supposed to start. I dunno. Anyway..it was cool to learn how the little diagnostic thingy works.
Cabbie2169

Definitely do the mode 1 & 2 tests. Do the ignition tests too. It's so easy there's no reason not to.
No, I don't think that's the way the '89 is supposed to start. It should fast idle for a moment and then settle down to normal engine speed.
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'80 DL 2 door, '89 DL Wagon

If you mean that it idles so slow that it barely keeps running, I feel your pain. It is especially evident when the car is stopped when not completely warmed up, and then restarted. My daughter's '91 has always done that, and I can't find out why. It has eventually become something we deal with. If that is the issue, and you find a solution, please post it.
The best thing I did which offered some minimal improvement was cleaning the throttle body.

and I can't find out why

I just have to ask. Have you done the self-diagnostic checks?
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'80 DL 2 door, '89 DL Wagon

Yes, I did check out and clean the Idle Air Control Motor.