This sounds a lot like what happened to me. It was my fuel system. The pickup in the fuel tank breaks/tips over, and it has to be replaced. Check to see if your fuel pump is working, etc.
I hope there are no dumb questions here...I got in my truck the other day and noticed that loud whirring noise you get when your power steering is going out. It got louder when I held my foot on the brakes. I realized my power steering resevoir was empty, so I filled it up with ATF. Since then...