Things I liked:
The suspense was exciting. I love a good thriller.
Things to improve:
Suddenly a bird hopped itself on the curb next to Keith and jerked it's head about in every which direction like birds tend to do, flapping it's wings a few times in a welcoming gesture.
Suddenly is unnecessary here. Just start the sentence with "A bird.."
apple red 1983 Jeep Cherokee Laredo
Every detail of his car is unnecessary. His old red jeep would be sufficient. The same thing goes for the girl's mustang. It only needs to be called a mustang.
"You stupid bitch," Keith snapped, delivering a hard blow to the girl's head, knocking her out and leaving her lifeless underneath him.
This line confused me a lot. I thought she was dead. You might want to add near lifeless to that line and perhaps give Keith a crowbar or something? I don't think he could knock a girl out with one punch to the head.
A bird perched itself on the trash can where the maggots and larvae were starting to migrate towards.
This sentence is confusing as well.
A bird perched itself on a nearby trash can that had become a migration spot for maggots and larvae.
In the line right after that, you wrote it's when the word should be its.
It's = it is.
It's = ownership.