I guess I forgot to post an update, but I changed the fluid and filter, added some Lucas stabilizer and haven't ever had a problem with the car on the transmission side. It got stuck in 3rd once for about 2 minutes, but I shut the car off and started it back up and it was fine. I've put about 7,000 miles on it since I've owned it and its been just dandy.

happy to hear the great outcome...

A little time, relatively small amout of $money & a saved transmission/vehicle...pretty good ROI for the time & $....

Thanks for the check-back update...

I had this once and all I had to do was adjust the TCC/Brake switch. https://www.gmforum.com/electrical-133/tcc-solenoid-switch-284972/