while accelerating the car feels like it is surging?

I bought the car Saturday and just today noticed that while accelerating the car feels like it is surging. The RPMs don't go up though. It's a very consistent surge and also subtle. It's not jerking. Also, I smelled gas pretty strong when I got out of the car. And sending outside of my car it sounds like it is revving while idling. Again, the RPM gauge doesn't go up. Sometimes there is a very short vibration felt while it is surging while idle.