Don't know if it's the same problem or not, but my wife's Montana did the "shift-kit" shift when it wanted to. There was no rhyme or reason; it seemed completely random. When it shifted hard, it shifted hard.
Anyway, we took it in for some other stuff and mentioned this. Somehow they were able to duplicate it and turned out to be a bad PC solenoid (whatever that is). Anyway, they're both GM products and the problems sound similar. Might wanna keep this in mind.
