What did the old fluid look like? Smell like?

When you drain & fill you only get about 1/3 of the fluid because the torque converter doesn't drain. If the fluid didn't look very healthy, you ought to do a couple more drain/fills after driving 25 or more miles in between.

Finally, when you ask stuff, it's important to say EXACTLY what you have. In this case the 4-cyl & V-6 transmissions are COMPLETELY different from each other.