2000 Chevy Impala hesitates

2000 Chevy Impala 3800 engine with 130,000 miles. After I start my car, it will sound fine but then maybe 30 seconds later the engine starts cutting out like its going to stall but doesn't. It won't happen every time and it will happen in reverse, drive, or when idling. It happens after the car has been off for more than an hour. I have to step on the gas almost flooring it and finally the engine will pick up to normal again and won't give me problems for the rest of the ride. The car runs and drives beautiful except for this one problem when it first starts up. To the ear it sounds like it's not getting gas and has no power at all and then it will have full power again after holding the gas pedal down for a couple seconds