my 97' has the TCC shudder too between 35 and 50 though only occasionally during acceleration.

(*^()*&%*&%#&*&O@:>P:*)!:L<"?#>!#O_)(!#)^!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!
I was having some of that shif prob but now it'* stopped...completely!
I had to coast in to my driveway and it has no gears at all! The fluid is corect color and level.

Can you pull the codes?

yea - no codes but the "p0440" gas cap one.

I took it to the place the rebuilt my 700R4 for the IROC and he said it had all sourts of codes, I guess my cheap POS scanner could not get them. Time to get a Snap-on scanner off of E-bay. Well it'* going to be about 2K to rebuild it. Tried to find on new but the best was off of www.gmpartsdirect.com for $1,400+ 700 core. So so much for that, and I don't want to get a salavge one for my car. I checked back after the hurrcaine and come to find out it'* been out of the car before, and they f'ed up the valve body and prob lied about putting in a new TQ conv. He showed me clear as day that some shop had marked what car it went to and repainted over it to look new. I hope it'* done by Fri, I have to go to PA the next 2 weekends.

Hey, I get TCC lockup issues everytime I try to get to highway speeds with the engine/tranny fluids warm. I have to shut the car off (at speed), open the door (to reset the ecm, or TCC), and restart and put it back in OD and use the cruise as my throttle (any manipulation of the gas pedal or brake pulls it out of OD lockup -which is really doesn't go into unless the motor/tranny haven't been run in 6-8 hours depending on the outside temps).
This is on my 1994 SLE.

Yes Pioneer.

Don't be afraid of really pulling hard under the front of the bottom seat.

The best way to drain the coolant if you just want to change the thermostat is to put a small hose inside the radiator and syphon out about 1/2 a gallon.
If you want to drain it completely, remove the bottom large plastic cover sheild and you will find the petcock on the radiator on the drivers side bottom.

I felt around on both corners but could not feel the drain, but I'll check again there after I get it back from the tranny shop. $2,400+tax!!!!!!!!!!

I got the seat out. But get this the P0440 is set due to the gas gauge showing full and the car knows-shown through the DIC that it'* not and get confused on how it should evap the tank- IE how much press and it sets the code(*).
GM tech bulletin 00-06-04-011A OCT 01