I have 9 stents in my right artery and when I exercise my blood pressure drops and I get dizzy.

It’s not advisable to exercise so hard that you get dizzy.  Your heart is unable to supply enough blood to your head.  Even people with normal blood vessels should not exercise that vigorously. People with heart disease should be encouraged to exercise, but need to practice in moderation.  Ask your doctor what should be your maximum heart rate target when exercising.