I doubt if the Napa fluid is causing the problem but it is the wrong fluid. Even if you drain it and put in Dexron II I don't know how you would drain the torque converter which probably holds 2 quarts. The whole system probably holds about 14 quarts.
You may want to call Joseph Industries in Ohio, tell them what you did and they can advise whether to drain the fluid.
There should be an oval plate riveted to the top of the transmission with the part #. It should start with 9020 or A9020.