2003 Mitsubishi Montero Sport - Transmission Drops Gear

Transmission dropping down a gear at highway speeds for no known reason

Thanks for the info. Won’t be looking to buy one of those.

A low level of trans fluid can cause that problem. Have you checked the trans dipstick?

When was the last time that the trans fluid was changed? In view of the vehicle’s age, that maintenance service should have been done 5 times so far.