Admissions committees at Yale, Harvard, and Stanford consider a range of factors beyond grades and test scores, including extracurricular activities, leadership experiences, recommendations, and personal statements. If you have a strong background in extracurricular activities and can demonstrate leadership skills and personal growth, you may have a better chance of being admitted. It is also worth noting that these universities may weigh your academic performance more heavily based on your most recent educational experience.
Overall, your chances of admission to Yale, Harvard, or Stanford are uncertain, but you may still be considered if you have a compelling personal story and can demonstrate a strong upward trajectory in your academic performance. It may be helpful to contact the admissions offices of these universities to discuss your specific situation and explore any potential pathways to admission.