Stalling Idle drops off after engine gets warm and the unit stalls.  No warning lights glowing.

No, not the oxygen sensor. A couple of things you need to make clear. What light flickers, then stays on? That can't be a sensor light, it would have to be the "check engine light" or an engine temperature light (for like when your cluster has no temperature gauge, but just the "red light").
At any rate, the sensor you changed is not the engine temp. sending unit for the instrument panel. I believe on your '89 there would be two sensors for temp. One is the CTS for the engine computer, and the other is a sending unit for the dash, probably a 1 wire connector. It could be at fault, but it wouldn't cause stalling, I do not think anyway.
If it stalls and won't restart until cooled, this is a symptom of loss of ignition (spark) caused by either a faulty coil, or faulty Ignition Control Module (the coil controller), or last a faulty Crank Position Sensor (this sensor used by computer to determine ignition spark timing). You could test if ignition is lost, by checking for spark right after the engine warms and then stalls. If you have no spark to a spark plug right after it stalls, this is the reason for stalling. Usually it is the crank sensor, rather than the ignition control module or an ignition coil. Your car has 3 coils anyway in a "coil pack", so if one coil went bad, you'd still have two good coils, but engine would only be firing on four of the six cylinders-could easily stall a car.
You should check for trouble codes whenever you have a problem. A code might have been set. Easy to check for codes on your car, just ask if you don't know how-only takes a jumper wire or even a paper clip works. good luck.

If you havent rebuilt the throttle body ,that would be my suggestion

tune up ,fuel filter,air filter,

I Have a couple of questions. First question does engine surge when idleing cold? 2. Does engine start quickly without a lot of cranking, Cold or warm? 3. Do you have funny smell at highway speed, or after you stop? With out this info and your imput, I would only be guessing. I am retired mechanic of 25 years. and would like to help if u need me.

Some "check engine" light in your dashboard? If YES, need to scanned the PCM (computer) to know exactly what fault code is stored there. If NO, the crankshaft position sensor may fail, causing engine stalling or a failure to start. Replacement or the failed sensor will commonly correct this problem.

Also, keep in mind that on the 2.7L V6 and 2.4L 4 cylinder, a defective Exhaust Gas Recirculation (EGR) switching valve may cause an intermittent rough or unstable idle engine.

Stalling synthoms... you can have a plugged exhaust, plugged fuel filter, bad airflow meter, problem with the ignition system, incorrect timing belt/chain setting, and failing fuel pump....I'm sure there's more but that should get you thinking.

Keep us updated.

Hi, car stalling problem often means the engine is not getting enough fuel and/or too much air. A cold engine needs a fairly rich fuel mixture to start, and to idle smoothly while it warms up. Any of the following could cause or contribute to this kind of stalling problem which i would not want to exaggerate until i get a clear picture of how the car stalls.

Does your engine stalls when you stop for a traffic light or when idling, or your engine just stalls unexpectedly while driving?
Answering the question will help me determine the cause of the problem.

ok buddy on the carb will be some sort of screw and idle screw turn this in 1/4 of a turn with the machine running until it idles at 1000rpm also the choke will stall the engine when warm the choke is only for cold starts get back to me more info or problems

sounds like the idle control vale is sticking when it is cold. It is located on the throttlebody right at the air inlet