Mitsubishi Repair: mit 3000gt 1998 automatic, overdrive switch, highway speeds

Question
pops in and out of overdrive several times in succession when cruising at highway speeds ~70-80 MPH, MAY DO IT AT OTHER SPEEDS BUT HAVENT NOTICED, ALL SHIFTING IS SMOOTH OTHERWISE,  95k MILES

Answer
RW,
The overdrive switch my have a little short in it.  Your problem sounds electrical, and most likely something simple.  You may just need to replace the switch that controls your OD.  Since your car is shifting smoothly, your transmission itself should be fine.  Have the OD switch looked at and replaced it necessary.  I believe the part number is MB484968.
Good luck!