IB Diploma vs. IB Certificates

<p>I've just finished my Junior Year of High School. Since I go to an American school, i am doing both the HS Diploma and IB Diploma. But Lately my grades have gone down drastically. My GPA last Year was a 3.83, but this year it has gone down to a 2.81. I'm not able to focus on one subject at a time, causing all of them to drop, especially IB Chemistry SL. I'm terrible at Chemistry. I take HL Eng, Econ, Phy and SL Math, Chem, Spanish AB. I am planning to drop IB Chem and do IB Certificates as i can bring up my GPA to >3.5. I'm planning to apply to US, to these universities: NYU, BU, Virginia Tech, Georgia Tech, University of Texas - Austin, CMU, Penn State, Purdue. </p>

<p>So with these conditions should I continue with the IB Diploma or Take IB Certificates by dropping chemistry and taking a normal HS course, with IB in rest of the Subjects?</p>

<p>Note: I'm deciding between Finance, Engineering and Marketing Majors. I have 6 science credits atm.</p>