After changing my ATF, I took a 240 mile drive to see if it improved anything, and it has! The shifts are a lot smoother.
However one problem remains, and unfortunately unrepairable. It's the solenoid that controls the pressure in the transmission. As a result, when the fluid is warm and I'm coming to a stop, the transmission drops out of gear, until I step on the gas again. The only way to get a new one is to get a new valve body...which means a second transmission. And I'm not doing this.
Now, two people told me what they've been doing to avoid the dropping out of gear. Every time they are braking to a stop, they shift into neutral and coast till stop. After that, put back in Drive and it goes in without any clunks or noises.
Is it okay for the automatic transmission to be shifted into Neutral when slowing down to a stop? Will that hurt/damage anything? (Spectre?)