I pulled a 2,000 lb trailer last week and my shift points changed a little and the fuel trims, etc also changed so mileage is still coming back up. I had a sunfire for a while and it would run to about 4,000 rpm for the first two gears for about 4-5 take offs if you got on it hard once. But it wouldn't give it everything that one time because it had been driven slow. really drives me nuts because they don't like to do what you want them to do when you want them to do it. The olds is pretty good about it though. At least they learn to shift a little sooner if you are nice and easy...unless you have a manumatic, then you shift it when you want.
i just have to get mine put together...