Thanks guys for the suggestion. Yes, I'll be installing the tranny cooler before the end of this year.

After figuring the mileage, it was the worst ever. I measured about 11mpg, and that's suppose to be mostly highway mileage (my normal commute to work is mostly city traffic). Well, it's been bugging me all day and after work, I decided to check the A/T fluid to make sure it was not burnt. Thankfully, it was still red, and no burnt smell. While my hood was up, I thought I would check all other stuff. Surprisingly as I open my air filter box, the filter looked fine, but there was a large unfolded napkin that was covering the whole air filter.

Indirectly, I think I might have just solve my stupid problem. I normally like to tuck in some paper towels or napkins in the corner of the engine compartment so that I can check the oil level and have something to wipe on other than my shirt. well, this particular napkin somehow had made itself into the air intake box (I've removed the air intake elbow from the fender) and was covering the whole air filter. I think that was the main reason why I was having such a hard time in keeping at 60mph as my engine was starving for air. Since I was running short on horsepower, the transmission was working overtime shifting up and down the whole time. Well, now that my air intake box is napkin free, it's like having an extra 20% improvement in horsepower. The only positive side to this story is that my air filter from about 6 months ago still looks very clean. Of course, I more than paid for it with the bad gas mileage @ close to $2/gallon of gas.

Again, I know I'll be installing a larger cooler anyway as an insurance.

Thought I would share my stupid experience so that others can learn from it. Moral of the story is to always check everything, especially before a long out of town trip.