I replaced the ignition switch and it seems to have fixed the issue. Only a long haul drive will tell completely. It has 147k miles. Also I noticed it shifts from first to second gear fairly firm. Enough that the vehicle will jump a bit when it shifts. Wondering if that is related to everything else

I was told this by a transmission shop in my town. I figured they would know since they specialize in transmissions exclusively.

Yeah, first gear is 3.06:1 and second is 1.62:1 so it can be a bit of a kick. I guess it depends on what you mean exactly by "fairly firm" and how far down the gas pedal is when this happens.

Okay that makes sense. Some folks say "I was told" when they were told by their neighbor or the seller or their dog.

Great news! Will look forward to the long test drive results.

​​​​​​Well it didn't fix it. I did a good 50 miles and all of a sudden the torque converter starts to disengage and then it momentarily jumps out of overdrive before immediately jumping back in. I'm now at a total loss as to what the heck is the problem.

So the TCC solenoid would just need replacing? Or is there a bigger issue if something is worn in the valve body? The ignition switch did not fix the issue and it still managed to disengage the torque converter and overdrive briefly on a longer road test I took. Still shifts fairly firm from first to second as well. Usually takes up to about 2500 to 2700 rpm before shift and I'm not really pressing the pedal hard. Other gears shift fine.

This looks like one of those issues that you could chase until the end of time. I wonder if you put a big ol' honkin' transmission cooler on it if the issue doesn't go away. It'* the long-drive part that makes me think that. I also wonder if it has ever had the shift solenoids changed.

I literally had all electronic components changed in the tranny. Definitely not the shift solenoids.

Going back and reading your original concern,it sounds more like tcc slip issue. if you can get a scan tool,watch tcc slip speed and when you get the condition to happen,command the tcc on ans see if the slip speed goes to 0 rpm. when commanded on you should see a drop in slip speed that will tell you electrically the circuits are working.then if it doesn't go to 0 rpm there is a mechanical/hydraulic issue internal to the trans. on some of these(right now can't remember years)you can put the trans in ,if i remember right, M2 and LIGHT brake torque,turn on tcc.it should stall the engine.if it does it may be a valve body issue.if it doesn't,it may need a torque converter also. Check the trans fluid for contamination. From what I've read,the trans fluid is new color is probable a bright red,but can you smell a something like "Hot brakes" in the fluid.
If so their might be an issue with a clutch. Hope you find this helpful.