No matter what gear I'm in, if I let off the gas I can feel the tranny go limp then flop the other way when all the slack gets taken out of the gears. Then when I get back on the gas, it flops back the other way and the car lurches. This makes it so I pretty much have to press in the clutch before letting off the gas, or getting back on it in traffic. Otherwise its just a series of uncomfortable lurches forward and back the whole way. Other cars don't do this so I was wondering if this is an NVT350 thing or if I have some wear issues.

Car is a 95 ESi, all 4 motor mounts are stock and in great shape.

The kind of obvious; but are you sure your front crossmember isn't loose, and that there is no play in any of your cv joints?

Yes. It's not suspension related in any way. It's all in the gearbox.

You get the same effect when the car is raised up on jackstands, in gear, and you turn one of the wheels (while blocking the other one). There is usually an inch or two of play then you hear the gears clack into place and get resistance.

This tranny just has an awful lot of play.