Idle surging when downshifting

[Canaan Jones]

I have a 2004 silverado 4.8 with a 4L60. When im slowing down and the truck is downshifting it surges really bad and tries to push me through stop signs and red lights. Sometimes it drops so much that it goes dead and even if i pop it in neutral while im slowing down it still does the same thing so i know it isnt the transmission or torque converter. I've had it tuned and it didnt seem to help anything. What do yall think it could be?

[sefiroxx]

Sounds like torque convertor may not be releasing. Probably some thing caught up in the tcc valve.

Have you checked the fluid and the pan?