doesn't act like it is getting fuel

When I start it, it chugs a few times, backfires under the hood, then dies.  It will do this repeatedly, then eventually will slowly start to act like it is getting gas, but when I first pull out of the driveway it will start to chug and jump.  It will then run okay for about two blocks then start chugging again.  After that it will generally run okay until I turn it off.  Then when I start it again, it is the same as the first time I started it.