I agree, check the fluid. But, if the shuddering you experience is like running over the rumble strips on the shoulder of a highway, then that's TC shudder. You may get away with draining as much trans. fluid out as possible, changing the filter and refilling with Mercon V.
You don't have a CEL on do you? Might be a mis-fire and not TC shudder.
As far as the hard 1-2 shift, if that is the original 94 trans and has not been updated, then I'd bet the 1-2 accumulator. I think a j-mod would def. help here as it requires the installation of the updated 1-2 and 2-3 accumulators. If you go this route, check the bore for the 1-2 accumulator while you have the old one out to make sure it is smooth on the inside, as they can develop a rough spot and will tear up your new parts and nullify any gains from the new parts. That and you will have to drop the pan yet again to go in and fix it.
just my .02
These are highly engineered precision vehicles, the first step in diagnosing the problem is to strike the suspected offending part sharply and repeatedly with a blunt object, then re-test.