will be going down road & car shifts all by itself, when is already in gear, sometimes does it 2-3 times. no one knows what causes it, as won't do it all the time. mechanic drove it a week and nothing. It goes like a sun-of-a-gun otherwise. Scared to go to far as transmission might fall out? Will I have to have tranny taken out and checked? As can't think of anything else to do!Hope someone can help!