"Will reading out loud help with speaking more fluently and clearly?"
I believe it will but it will take time and you must be patient with yourself. Doing it every day at the same time will help to develop a routine.
Listening to stories on tape too will help you to understand how other people raise and lower their voices. You might like to copy them, say it as they say it, like one would if learning a different language.
You could also try talking with a mouthful of marbles. The more you struggle to make yourself clearer the clearer you will become.
While reading concentrate on p-r-o-n-u-n-c-i-a-t-i-o-n.
Work at it. And if you feel or look silly in the mirror, don't be afraid to laugh at yourself. I think you just need to relax more. And be careful with those marbles. lol