Mitsubishi Repair: tranny rouble, transmission control unit, overdrive switch

Question
i have a 1993 mitsubishi mirage 1.8l he car runs up to 40mph no problem 1-3 works fine but when it goes for overdrive it does nothing ell for the last week it did nothing i took it to a shop they said the trans was sho and needed to be replaced now today i took it out and it went into overdrive just as good as new also i left the car siting for like 3 months and it drove fine before i parked it and as soon as i started using it again it was slipping out going into second for like 2 hours then that stoppd and never did that again any sugestions?

Answer
June,
At the least, you should have your tranny fluid drained and refilled with the factory recommended fluid, and have the filter replaced.  You should also have the overdrive switch and the transmission control unit inspected as well.  As a test, accelerate slowly to see if you go through all the gears.  Sometimes jack-rabbit starts (hard accelerations from a dead stop) can put excessive strain on a transmission. Since your car is 13+ years old, it can cause issues.  Also be sure to come to a complete stop before going from reverse to drive.
Good luck!