96 taurus LX wagon tranny problems

3.0 Liter V6 24 valve Duratec. Not sure which tranny I have, but code on driver's door under TR is XLLUU

Tranny does not engage in drive when accelerating from a dead stop. However, when put into 2nd, tranny responds normally and can then be upshifted into drive for continued normal operation, until the next stop when the whole process is repeated. Also, tranny responds normally when overdrive is off. Any and all advice appreciated. Thanks, JBR

TRANNY=AX4N

PLEASE HELP! THANKS, JBR