If a 1999 Montana is shifting hard from gear to gear should the throttle speed sensor be replaced and if so where is it?
If it is the same problem I had, it is in the transmission and requires the pulling of the transmission. This is a comman problem with some Montanas. It might be the pressure control solenoid located inside the valve body of the transmission. Yes this is probly your answer. These cars have this problem alot. I work for Gm and I know first hand. I was having the exact same problem two weeks ago. I replaced the pressure control soleniod and the transmission now shifts as smooth as it did brand new.