Recently had 1996 taurus trans. Overhauled. Gear still slips between 2nd and 3rd when warmed up but not cold. Mechanic said he only replaced the burned up clutches but nothing else.

In my 2000 Taurus, with an AX4N transmission, I only use Mobil 1 Synthetic Multi-Vehicle ATF or Amsoil Universal Synthetic ATF. They offer superb frictional characteristics, resulting in perfect upshifts and downshifts, regardless of hot or cold weather. Consider giving them a try. Afterwards, disconnect the negative battery terminal overnight, to force the PCM to relearn all shift points.

I would double check your fluid level.