My car will only start if you pump the gas while cranking it.

The first start of the day the car usually starts up right away and the longer between starts the better. But to start it after that I must pump the gas while cranking it. Then a cloud of blackish smoke comes out and stains the ground. Also my car accelerates on its own. Up to 45 miles per hour. This is a problem because it is fighting my breaks to stop. And my RPMs fluctuate greatly. One second it will be accelerating on its own then it drops about 1000 RPMs and coast to a stop. I dont have any idea what could be doing all of this.