So, it's been a while seeing as i had to unexpectedly sell my 94 (full -sized) Montero LS. Looking to jump back into the Mitsu ring like this Saturday with a 2000 Montero Sport XLS, but it has an issue.

According to the owner it will kick out of overdrive at speed into neutral. It'll then have to be put into reverse, then back into drive and will then move fine. Think this could be a lack of fluid (or the wrong one), a solenoid, or 3rd to 4th clutch gone bad...

It drives fine some days. The only issue is when it shifts into overdrive...

 

Not sure if they have an overdrive electronic module, you might want to look into it. You might also pay for a diagnostics of the trans with the proper diagnostics tool. A trans shop will ask you a pretty penny to repair, but if you can take the trans down yourself (not difficult) and have a reliable mechanic or friend that knows how to rebuild trans, you can buy the master repair kit, which is around $400.00, and have the valve body rebuilt (including solenoid check), which will set you back some $200.00. For approx. $1,200.00 you could have the trans properly repaired.