Since the noise is present in every gear, and I assume while IN gear while sitting stopped, the only thing that is spinning in all situations is the pump and torque converter. Pumps very rarely are ever the cause of noise in these transmissions on their own, but a bad pressure control solenoid or boost valve or a few other parts can cause it to whine. There is a small bearing on the inside of the pump rotor that could also be at fault and cause a faint noise but again not really common. If the torque converter was making the noise it would get louder with a heavier load such as accelerating. I know you are pointing towards trans and your servicing the trans and adding a trans cooler appears to have had some effect, have you checked ALL of the engine pullies? Though the noise may even sound like its coming from the trans I have worked on numorous grand prixs with the non supercharged engine and before and after a trans rebuild the noise was present and after listening over everything with a stethoscope a few idler pullies are generally to blame. Im not saying this is the case for you, but a cheap stethoscope is probably $5-$20 and you can pinpoint exactly where the noise is coming from. DONT start with the transmission bellhousing area as all engine noises will carry through the engine and echo into the trans giving you a false sense of what is making the noise. Start with all the idler pullies on the engine, AC compressor on and off, alternater bearings, and power steering better be quiet since its new! After you check those and they are good then you are left with the trans. Here is something else you can try.... Once the noise is obtained while you are sitting in the drives seat pull the shifter into manual 1, this will create near max line presure and cause the pump to get loud. Does this noise sound like what you are hearing but louder? I appreciate the long post as it greatly helps out and I will do what I can to help out!
