Cook pasta according to package directions. Meanwhile, in a nonstick skillet, saute the onion, peppers and garlic in oil until tender.
In a small bowl, combine flour and milk until smooth. Add to vegetable mixture.
Stir in the seasonings. Bring to a boil; cook and stir for 2 minutes or until thickened. Reduce heat; add shrimp and basil. Simmer, uncovered, for 3 minutes or until shrimp turn pink. Drain pasta; place in a large bowl. Add shrimp mixture and toss to coat