Will a "D+" in AP calculus AB affect my chances significantly.

Ok guys here’s the story: I took a really hard course load junior year and got a “D+” in AP calculus AB all my other grades were pretty good (mostly a’s a few b’s). I opted to drop the class and take it at a local college (according to GC the grade I get in the college course will factor into my GPA and replace the D+ I got first semester). It looks like I will get an A in the college course. I figured that my UC/CSU GPA will be around 4.27. My ACT score is a 34. For schools like Cal Poly SLO, UCSD, UCSB, and UC Davis will the D+ really harm my application even though it won’t be factored into the GPA (the college course A will even though the D+ will still be visible).

You’ve already answered your own question. It won’t be factored into your GPA. Your grade will be replaced.