Yes, the fluid is within the fill marks, and the transmission was cycled through the gears to ensure a correct fluid level. Then yes the next thing in my diagnosing will be to run a pressure gauge and vacuum gauge into the car and see what my readings are while driving down the road and while going through the gears. I get the feeling with the way the car drives in 3rd that there is a pressure loss or restriction in the valve body from the water and that's why 3rd gear is so weak. What size thread is the port for the pressure on the side of the transmission?