1992 Pontiac Bonneville My car won't start.

I was driving down the road the other day and my car started sputtering and then died while I had the car in Drive. I coasted to a parking lot and parked it there, then tried to crank it back up. It acted like it wanted to turn over, but just wouldn't make it. Sometimes it actually would turn over and hit about 1 1/2 RPMs and then die again. I left it there overnight and returned the next morning to try again, and it started right away. I went to start it up just now, and it's doing the same thing as it did before. I can rev it all I want when it DOES turn over and it still dies, so I'm not exactly sure what the problem is. I recently replaced the speed sensor on it, I don't exactly know if that would have anything to do with it though. Please help me!