2002 Chevy Truck noise

I am not a certified mechanic and right now have my own question posted here but two experiences I have had with flapping sounds one- involved the rain guard (clear brown plastic guard against water drippage) flapping with a hair line crack in it, I replaced and it was fine, and two, inside the wheel well, the plastic/rubber that that covers the wheel well top and sides (behind/above is the engine) came loose because of the plastic screw-like bolts they use to attacth this/these pieces came loose. Check it out? Just one lats guess, but maybe a vent issue on that side? Happy to try to help,
JJC :idea: