How much came out in your drain?
Reason I ask is that I believe there is a little over 10 qts in the whole system and the way I changed my 4.4 fluid was to drain and change the filter, refill per the procedure of waiting for proper temp to top off and then repeat the drain procedure another 4X to completely eliminate/dilute the old fluid to nil by the fresh fluid.
I used AMSOIL Signature ATF at about 82K miles (no issues at that time) and I'm at 96K with smooth shifting and still remain issue free.
Mike