I just installed a new carburetor on my 69 Mustang Coupe Grande 302 V8. After installation, the car accelerates up to 45 mph without even touching the pedal. When I turn the car on, it idles extremely high like someone is slamming the pedal down. When I put it in drive or reverse it kicks and can get up to 45 mph. I've tried adjusting the idle adjustment screw but it doesn't do much. I don't know enough about carburetors so if anyone else has had this problem or knows what might be happening...

69 Mustang 302