I Recently ran into a problem with my 05 envoy slt 4x4. It suddenly lost power in first gear. Seems sluggish and throws code P0756. So I changed both shift Solenoids and changed the fluid in the pan, but no change any advise about what might be going on or how to fix would be greatly appreciated. I've searched all over the internet. Same answer people coping and pasteing about its mechanical. But where to start after the change of the solenoid.