Random Transmission Clunkiness

transmissions
#1

I have a 1999 Honda Passport (Isuzu Rodeo) that I drive only a couple times a week. About 3 times a year, the transmission will act out. The most common is it will rev quite high before shifting then slam into the next gear. It has 110k miles; I bought it at 80k miles and don’t know the maintenance. I haven’t done anything.



I am hoping a transmission flush will take care of this???



Also, I live in a place with a lot of steep hills and mountains with switchbacks (10 and 15 mph). I often drive in 1st or 2nd down the hills to save brakes.