88 K5 Fuel Problem
 

My 88 is flooding while driving. It runs fine sitting in the driveway, but when you get going and start getting in it to build up speed, it dies. After a few minutes you can hold the gas all the way to the floor and it starts, but it backfires and throws out black smoke. I have replaced the inline filter, relay, distributor, and distributor cap. Can anyone help me please?