My 1992 Mazda Mx3 GS (V6) will run but will not move in drive. It will move in reverse though. We rebuilt the tranny, and replaced the ecu and speedometer sensor. Any ideas what it may be? It is an automatic.

Have you tried checking the shifter linkage for any possible bends or jams? Also, some cars have a fuse that blows that allows reverse but no drive, sounds silly, but 92 and up kia sportages often have this problem, not sure about mazda though.