2000 Chevy Silverado

The truck was used yesterday and had no problems at all. This morning leaving for work, it did not want to start--like the battery was about dead. After a couple tries it fired right up. On my way home from work, same thing happened. I work "on top of the mountain" and on the way down, the truck did not want to stop. With my foot off the accelerator and on the break, the rpm kept steadly rising. I drove it around the block to see if the incline was adding to the problem. Even while stopping at a stop sign, the rpm kept rising. When it was time to go, the truck seemed like it was driving itself. It spead up to 25mph without anything on the accelerator.