Power loss

I have a 2004 M/T 8 with 90k on it. As of last thursday my car began having power loss issues. When I started the car up that night it started just fine and then the rpms gradually began to drop. When I gently apply the gas it would accelerate like normal but if I smashed the gas the car would struggle intermittently. It would have a sudden burst of power and then lose it on and off. When I stopped to gas up I had an hard time starting the car back up. I thought it wouldve been an issue related to fuel delivery so I checked the fuel pump sock and it was clean. A friend was thinking maybe the altenator and that checked out good as well. Im at a block now. Any help would be appreciated. Thanks guys.