I noticed it might be slipping in lockup.
I will let it coast then give it throttle (not much throttle) but when I do give throttle it seems like the stall comes unlocked (just for a split second) before the rpms become steady again. I had this stall for 31k miles and it (or the trans) hasn't been like this before.

I am also having issues with the 2-3 shift under WOT.

I originally was thinking I just need a new trans but I would like to rule out the converter as an issue. Could a bad converter be causing these issues? Bad lock up clutch?

 

I had a 'lockup' related issue, cruising on the highway if I have it any gas the rpm's jumped ~400 and I didn't seem to be able to accelerate. I then started having a slip between 2-3 and 3-4. Turned out to just be the 3-4 clutch pack being burned up.

 

Well my 2-3 WOT shift is bouncing so maybe it is build trans time.
Thanks for info.

 

Since you are now also suspecting your TCC is slipping in addition to your 3/4 clutch, I suggest checking the trans line pressure. The guage is readily available for $40 on ebay, or a local trans shop can do that for you.

 

Honestly mine has always been a little finicky going into lockup. Is your car tuned? Do you have any idea what the settings are on the transmission side of things?

 

Yeah the car is tuned. I know what you mean but it didn't act like this the whole few years its been in the car. Its set to lock at 40mph. I don't have access to settings I never got into tuning like I wanted. Maybe its just the trans going seeing how 2-3 shift is messed up. I think I'm going to get a built trans. I got 124k out of this stock one not bad!

 

If you don't have good tuning/diagnostic equipment yourself, I would find somebody who does - even an up-to-date local tranny shop. Pinpoint the problem before making substantial expenditures on hard parts.