[rlj51]

I have a 1990 Tbird LX, 3.8 Auto. It has similar miles as yours, about 140K. It used to do that same thing, where it would rev up for a second, then suddenly engage and launch the car forward. It would only do this when cold as well. Well it started to get worse and worse until the tranny would hardly engage at all. Then it dawned on mr to check the transmission fluid. The dipstick showed nothing at all! So I filled it up with fluid, and now it engages properly. It turns out it is leaking tranny fluid though. I think it needs a new gasket for the transmission oil pan. That seems to be where it is leaking from. So hopefully thats the problem, and the transmission itself is fine. I went down to a reputable transmission shop in my area, and they said that the AOD transmissions were actually pretty reliable.