What do you mean that the shifting is screwy?

Do you mean it slams into 1st and 2nd after holding the gear too long or will not shift at all or what.

I think the Transmission control unit is under the shifter but don't quote me. If I'm thinking of the right part, it's the one that gets screwed up when someone spills the big gulp on the shifter.

I had the hard downshift problem which was mostly fixed for years but comes back once in awhile. I know how to work around it so it is very seldom. IN my case that involved changing a bunch of plastic valves in the tranny 2 times under warranty thank god.