Is that normal for TB's? Every other vehicle I've driven (including pickups with the 4l60e) have locked up the converter while cruising down a 45 mph road, but my TB doesn't seem to ever lock the converter unless I'm going at least 60 mph. I've even bumped it down to 3rd on a 55 mph road and it still leaves the converter unlocked. It drives fine, doesn't have any codes, gets 'normal' gas mileage, fluids are all the correct color, etc..... It just doesn't seem right to leave it unlocked so much and could be leaving some MPG's on the table.