This morning the truck drove perfectly at startup without my heating up the transmission first. At this point I am going to adhere to the time-tested adage of, “If it ain’t broke, don’t fix it.” The atf is a perfect red color. The hot plate I used is pretty weak and was positioned about 12 inches away from the pan. I doubt the oil was heated to a higher temp than it gets under normal driving conditions in the triple digit (F) temperatures we get in Fresno this time of year.
When I emptied the old ATF I got about 4 1/2 quarts. The manual says the capacity is 4 quarts. Anyway, the old fluid was less than one year old.
At this point, the only thing that makes sense is that the old filter got clogged (disturbing in itself) and the tranny was starved for fluid, hence the slipping, and the atf took it’s time getting to the torque converter. Feel free to offer explanations that might fit the behavior described previously. The band adjustment error is not germaine to the main problem of slippage at startup and can be ignored.