Coca-Cola used corn syrup before New Coke was introduced. People just didn't take note of the change. New Coke was formulated to taste more like Pepsi after Pepsi gained a lot of market-share with Pepsi, Diet Pepsi and other properties.

Lots of people like Pepsi because it is sweeter. When testing New Coke, the product was a hit but Coca-Cola failed to inform taste testers that it would be replacing the original formula. But, Coca-Cola didn't realize that their product had such emotional and patriotic value. When the original formula was replaced by New Coke, americans felt they had lost a part of their history and identity. When Coke Classic was re-introduced, the first cans sold were made before the product was pulled off the shelves. It only took 3 months (I think) for Coca-Cola to re-introduce Coke Classic. In cans, the product can last quite long. These cans had Corn Syrup as the sweetener and were made well before the initial pull.

New Coke is now sold as Coke II in select markets (we have it). Interestingly, Diet Coke is formulated to taste like Pepsi, and not a sugar-free version of Coke Classic.

I did a report on New Coke in high school business class.