Got around to trying to save the 4L30E in my Trooper.
The truck would drive and shift fine until it would reach operating temperature. Once it got up to temp and had been driven a mile or so, first gear began slipping to the point that it would not go anywhere.
Pulling to the side of the road, turning the truck off for 10 seconds, restarting, and then continuing would get you roughly another 500 yards or so before it would slip again. My neighbor (a far better mechanic than me) and I both agreed that there had to be some sort of circulation issue causing the problem.
Tonight, we managed to take some time to bring the truck into his shop. I was not encouraged by what I found.
Chunks of metal as you can see all over the pan. The filter was clogged up something fierce as well. We did our best to clean things up, and replaced the 1-2 shift solenoid (my neighbor bench tested the old one and it seemed to check out according to his Mitchell software - but we replaced it anyhow)
We unhooked the transmission cooler lines and flushed the integrated cooler out as well.
Put a new filter in, topped it off with Castrol Import Transmax fluid and a bottle of friction modifier.
Took it out for a 20 minute drive and she shifts like a champion.
I will fieldtest her in traffic and on the highway tomorrow. If she passes, she'll be the new daily for a while!