Yes, I believe this would impact your chances at admission. Your essay is NOT “strong” if you use horrible punctuation. You have to figure out a way to cut words. How much over are you? Do you know someone (many a writing teacher, a counselor, or a parent with good writing skills) who can help you edit your essay? Often there are unnecessary words you can delete or ways you can rearrange sentences so that it still says the same thing but with less words/characters.