Anyone ever experience this

Perhaps the trans is slipping?

What stall speed is your converter?

Did it do this before the trans rebuild?

Is the trans fluid at the correct level.

Get an infrared thermometer and go for a drive. Use the brakes lightly, if there is a hill in your area and you can coast to a stop going up safely (ie without using the brakes to stop) put it in park and check the temp of all 4 drums / disks


If you really have a dragging brake that is keeping the car from moving correctly, the temperature will show it