Preheat the oven to 225 degrees. Pop all four bags of plain popcorn, and place in a really large heat resistant bowl. In a small bowl, combine 2 packets Kool-Aid and 1 teaspoon baking soda. Set aside. In a medium saucepan combine sugar, corn syrup and butter. Bring to a boil. Let boil for three minutes stirring constantly, then remove from heat. Pour in Kool-Aid and baking soda mixture to saucepan and stir in carefully. It will expand a bit from the baking soda so be careful not to get burned. Once it is mixed in well, pour immediately over the popped popcorn in your large container. Stir well until evenly coated. Place popcorn in oven for 10 minutes on bottom rack. Remove and stir well again. Repeat the 10 minutes in oven and stirring 2 more times for a total of 30 minutes and remove from pot to cool on parchment paper.