So I just rebuilt this transmission myself out of my 1970 cadillac deville and off the line from a stop it shifts perfectly. But when i come to a stop and right away try to take off again, it shifts vs soft with very low shift points. But if i come to a stop for about 20 seconds then take off it shifts fine. I checked fuild level with both the dip stick and unbolting the pan to see if it was just above the pan rail. I also replaced the fluid and have to pull the trans coming up to fix a small leak. I checked that vaccum is getting to the modulator which is a new adjustable unit and i even did a line pressure test with nothing to find out of line. So at first I thought the trans was too full and it was foaming the oil but it wasnt. Then i thought maybe the pump was going out but nope, passed the entire 1970 service manual checks with flying colors. Does anyone have any idea what it going on?