What kind of T/A's do you have??
Are they the TA street tires or something??
I've got AT KO 31's on my 97 Ranger 4x4 and my wife's got AT KO 31's on her 98 Explorer, and neither one of us have noticed anything bad in the wet with these tires. This is in marked contrast to the Firestone's.
I'm not sure what the issue is, but whenever you drive in wet conditions, you have to adjust your driving style. Even with a limited slip, I can smoke the rears on my Ranger any time I want - but I don't. When it's wet, I take special care to accelerate more slowly (5 spd manual).
I take it your Ex doesn't have the fancy transfer case with the auto lockup?? It's difficult (though possible) to get my wife's 5 spd auto Ex to break loose in the wet. In the dry, you can get the limited slip to chirp if you get into a tight turn and punch it, but that's pretty abnormal.
Check your tread depth, maybe??
Best,
Brian