doesn't want to shift out of any gear w/o chopping the throttle

[its turbo time]

Hey I had an LC 2 in my 86 t type and right before it got in a wreck it was taking forever to shift, or I would have to chop the throttle to get it to do it and now that same engine is in my brother's 85 GN and that tranny has alot of miles on it as well and it is doing the same thing. We are going to rebuild the tranny no matter what but I was just wondering if there is anything I can do to it to make sure it doesn't start doing this again. Thanks for any help.