Agree with plugs and vacuum leaks. Also, did you dump out any of the tranny fluid from the TQ when you pulled the motor? I've never done a Subby, but all other autos I've installed, I have poured a few quarts of tranny fluid directly into the TQ before installing into tranny. Other than that, I would have to agree that it's a pressure problem. Any idea on what the pressure should be? Can you tee in a guage to outgoing cooler line? I hate diagnosing AT's. There is some kind of magic juju that happens in those things.
