I was waiting for your last post as what you said above was not going to fix this, but I did not want to discourage you. Again, only a full scan with a trans function scanner will confirm tcc engagement, solenoid command and internal/tcc slippage. The TPS has on occasion also caused this, but that would be guess work. You must see by now there is no " work around" for diagnosing this issue. I've run my GM cars at 250 degrees and the tcc is un- affected, your temps are not the issue here.