My engine stalls at idle or when slowing down?

Well I would check fuel pressure as a possibility and also suspect the torque convertor solenoid.

Did you say there is a check engine light on?

After 150,000 miles if the job was given to me or I owned it I would still do the same thing. I would first check the level and cond. Of the fluid, then check the PCM and TCM for codes. If none I would moniter all the clutches and test all the sol. Pack valves for function. Bt then I would know what I need to know.
While I had it out and apart I would clean out and check all the valves in the valve body to feel them. Then after the valve body was apart I would use croucus cloth to wipe them down and clean them, replacing any suspected parts. Not just the valves that are part of the torque converter clutch control system. All of them. I would not use a torque converter unless it was a new one. It's internal clutches are not serviceable any longer. I would already know that the solenoid pack was ok not because it was just replaced but because I tested it already before I took the unit out. Then I would seal and reclutch the unit and check all the gears. Since it is AWD it would take about an hour longer. Then I would backflush the cooler and lines replacing anything that failed. Flash or replace the TCM and using the DRBIII quicklearn the new TCM. Roadtest. If it was ok I would keep it overnight and check it cold. If ok then I would turn in the RO and the keys and start another one the same way.
The valve body valves are checked by working them in and out to see if they are sticking. The torque converter is checked using a stall test. The 150,000 miles fact is the most important evidence.
I hope everything turns out ok. They built that unit to last 100,000 miles at the most. There is no stall test that will point out the problem your having intermittantly, but the new converter must be broken in with either the DRBII or DRBIII. OK.

I read your question and thought why is the transmission thought to be the problem? I said to my self if the engine was idling too low or had low power maybe there was a problem like a sensor or idle speed motor or dirt in that area, and what do I see, Yes you can clean it, and clean the bore that it mounts into and the blade and throat of the throttle body it screws into. You are on the ball.
But if the windings or controls for this motor are not correct, you can see it with the scanner. All day for years I repaired electronic transmissions and the torque converter locking up was a rare event. How does it run? Ch112063 my name is Joe

Go for it. I think you have 1. Low hydraulic trans. Pressure(o-ring may help). @. Problem with engine or converter. We will see what happens, thanks for the message. Joe

Hold the gas pedal down 1/4" to get it started. After disconnecting the battery, the Engine Computer will have to relearn "minimum throttle" before it will know when to be in control of idle speed and to give you the nice idle "flare-up" at start-up. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals. Next, measure the battery voltage with the engine running. If it is not between 13.75 and 14.75 volts, measure the voltages on the two small wires or terminals on the back of the alternator. The engine must be running during those measurements.

Have the alternator load tested and check wiring back to the ignition switch

First check for blown fuses. If there is one blown, check the wiring harness under the battery tray. The normal rocking of the engine can cause that harness to slide back and forth and wear through the insulation and paint until a wire grounds out. Next, measure the voltage on the dark green / orange wire at the coil or coil pack, depending on the engine size, or any injector. You should see full battery voltage for just one second after a helper turns on the ignition switch. What's important is if that voltage comes back during engine cranking. If it does not, suspect the crankshaft position sensor or the camshaft position sensor.