Bring a large pot of water to a boil and cook pasta according to package directions.
While cooking pasta, dice the chicken, peppers, and onion into bite-sized pieces.
Heat a large skillet over medium heat. Add 1 tablespoon of oil to the skillet.
Add the chicken to skillet and sprinkle with the fajita seasoning. Cook, stirring often, until no longer pink, about 6 minutes. Remove from pan and set aside.
Add remaining tablespoon of oil to skillet and heat. Add peppers and onions to skillet and cook until tender-crisp, stirring often, about 5 minutes.
Return chicken to skillet. Add in the cooked pasta, sour cream, salsa, and cheese and stir well to combine.