OK. I've posted here before on a rough idle, and the main symptom has been resolved (thanks to all that posted, especially Maurice!).
However, this did not resolve another, now independent issue I had.
When the car is cold, I start it, go into gear, and off I go. No problems starting.
When the car is all the way warmed up, I start it, and it has no problems on the start. Engine is as smooth as silk, RPMs are correct.
Then I go into drive, and sometimes (and only sometimes) the car hesitates to the point I think it will not go on. This only lasts a couple of seconds, and then car behaves as if nothing has happened. Smooth as a whistle, all the power in the world. It only happens once, and only right after I started the car.
The ONLY other symptom I have, and I don't know if it is related, is that the engine idles high and rough in park, but only when warm, and only in Park or N. In gear, everything is perfect.
Could it be a bad switch at the transmission? The hesitation can't be a leakdown, because the startup is perfect. If it were a fuel pump check valve, it would also happen when cold (never has). Or something in the transmission itself?
Injectors, accumulator, OVP, gas filters, secondary ignition are all new, OEM. 1989 model, 98k miles.