It does not flair up on the one two shift like a bad band. It seems to be eletrical. I drove it 30 mi. today and it worked fine. It never has a problem once it is going 45 mph+. When it messes up it is like you slam on the brakes. Two different times it did it when I first started it and backed up, stopped, and then as soon as I put it in drive it just shook hard and stalled.