Why won't my 2008 Ford Fusion take new car batteries?

So 3 weeks ago my cars airbag light cut on. I didn't think anything of it. So the next morning my car wouldn't start. My neighbor gave me a boost and away I went to work. My airbag light cut back on while I was driving to work. After work my car wouldn't start. So my dad drove to my job to give me a boost. It started and I drive home. I looked in my car manual and it said if the airbag light cuts on to turn the car on for 10 seconds but don't start it. Wait for the airbag light to go off. Since that day I've been waiting 10 seconds and the light has cut off. I went to firestone to get my car diagnosed and they said it was my battery. Not my starter or my trans. I went to walmart to purchase a battery. My dad put the battery in and the car started but wouldn't accelerate even when I push the gas pedal to the floor. I went to get my money back. I then went to a different walmart and the same thing happened. A week later I went to the Ford dealership and they told me it was my battery. I purchased the ford motorcraft max battery. And it still wouldn't accelerate. I'm frustrated because these mechanics can't tell me what's wrong. Someone please help!

So the engine turns on, but there's no acceleration when you put it in drive? That is obviously not a battery issue and surprised that a Ford dealership can't figure it out.

You're blaming the battery for something that's your own fault. New cars use an electronic throttle body. When you change the battery, you MUST do an electronic throttle body relearn procedure. Read this post.

http://ricksfreeautorepairadvice.com/ford-throttle-body-relearn-procedure/