how are 3500 stall conveters sopasto act

In your first post I read like your saying it does nothing until all of a sudden after you get the revs up it grabs like you dump a clutch on a stick shift. Am I reading it wrong? If that's what it's doing something's wrong with something cause no converter will act that way. It should take off smooth. Not jerk. Jerking is generally a problem with a clutch pack not engaging. Just because it's new doesn't mean it's right either. I have been rebuilding torqueflites for over 25 yrs. and you wouldn't believe some of the screwed up crap rebuilds I've seen.