A week ago I did a trans. flush on my system. I installed Amsoil Synthetic ATF. It started to cause the tranny to slip when the engine was cold. I thought it was causing the slip, was because there was too much fluid in the system. So tonight I drained a little bit out of the system. After that it was still slipping. It's a 01 f-150 with the 5.4 and 66,000 on the motor.
I thought that I would ask for some advice.

Thanks