[jsbihn]

Ok,
So if I understand correctly, you are stating that the transmission worked or works fine except in between gears? That when you shift from say 1st to 2nd it will stay rev or stay in nuetral longer?

I assume that you installed the tranny and replaced all fluid that go with it?
This is a common problem if the fluid is too low.
Also did you check to see if the trans cooler is leaking?
And also did you check to make sure that it was pressurizing and such?
The trans might be good but if the fluid isnt getting there........

Also how long has it been since you have cleaned your TB and MAF?
This might be a solution.
I know it might sound stupid but alot of times the MAF doesnt get the right signal in between shifts and it over revs.