Hi all, Now that it's gotten colder outside, my 2000 Silverado has been shifting differently. Up until now, it always shifted at normal RPMs. Now, it shifts at a normal RPM from 1-2, but it will hold 2 and 3 up to a much higher than normal RPM before shifting. In the morning, I start out on a 25mph road and it will stay in 2nd gear up to 30mph (2500-3000rpm I think) and never shift. Even when I let off of the gas when I get up to a red light, it will stay in 2nd and actually engine brake like a manual. It only does this when it is below about 20 degrees out. When I leave work, it shifts normally as it usually warmer outside by then. And if I hit a warm morning it will be fine also. It's got a 5.3 with the AutoTrak 4wd if that matters. Anyone else experiencing this? Of do I have a problem?