Cool, if it has a torque converter, then it's probably either a torque converter seal or o-ring, or a broken torque converter. Your honest best bet is to pull the transaxle and take it to someone to fix it. If you just take the car in it's usually in the neighborhood of $1000 or more, but if you can take the tranny off yourself and bring it in, it shouldn't be more than $200, and may even be less.
I started to replace the torque converter seals on the t-bird today, and the parts cost $14.04 from FoMoCo.
Good luck - I ended up getting rid of my last FWD car because I couldn't get the CV joints out of it to pull the tranny when it started acting up. But I was young, dumb, and full of a lack of automotive knowledge, but it remains that I have no experience with transaxles, and only very little with transmissions in general. I just know that you'll have to pull the CV boots and maybe the engine to get the transaxle off, but you can rent a hoist fairly cheap. (Cheaper than that $1000 at the tranny shop) or you may find a good deal
1997 Black T-Bird LX 3.8, custom painted interior, hand stitched vinyl backseat, oversized K&N cone filter, air silencer removed, painted some engine components, door solenoids for shaved door handles, Black Widow security system, wired to open Driver's door when disarmed, Dynomax 2.5" exhaust, battery box moved to trunk, custom grill inserts