I don't have a bench tester.
I only unscrewed the solenoid pack to look inside.
The filter screens are not dirty, the three return springs are not broken, the gasket worn a little, I did not touch the 4 coils.

They have a rebuild kit for whats I listed above.
I put everything back together expecting the problem to be there (not fixed).

 

Oh one other thought check your TPS signal and make sure its reading correctly. The trans shifts when its told to by the computer based on various readings including TPS and RPM. The solenoids react to what the computer is commanding. I would say I am 99% sure you wont find the issue in the valve body, if that was the issue I would suspect way more symptoms then what you described.

 

I have ordered the Borg Warner solenoid pack, and the two speed sensors.
I'm waiting for them to be shipped to my house.

You are right about start with the smallest thing first.
I might not find the problem in the valve body.

 

Just in case you do remove the valve body, you have to be careful that you disengage the link to the parking pawl. It's on top of the valve body so you can't see it when you take the bolts out. If you pull it down a bit you'll see the stainless shaft. It's spring loaded and just held on the pawl by the spring tension. You can get a screwdriver on it and push it back while you pull down on the pack. It will disengage and you're good to go.

Be careful putting it back in. I reassembled mine and didn't get the shaft in the right spot. As a result, the spring tension was transferred to the shift arm. It felt 'springy' when I moved it. In other words, when I moved it from gear to gear it wanted to return to a home position. I had to pull the transmission back out to reseat the shaft.

 

Thanks for the useful information.
I will try not to make the same mistake.

 

Update:
I replaced the solenoid pack, input sensor, and output sensor today. It did not fix the problem.

I'm so tired of these cars. I don't know if I will remove the valve body or not.
If I do, it will be in the summer.

I used my scanner to read the Throttle Position Sensor. It reads 10.9% at idle. Is this sound normal for this car?
I don't think it's the TPS that cause the problem, but I'm just curious.