Why is my car acting as if its struggling to get gas? on 2002 Mercury Grand Marquis

There are no diagnostic codes on the car and my check engine light is not on. While I'm driving it will start giving the feel like my car is running out of gas. Once it sit for about 20 mins. Then I can drive it until it act up again. I've had my right catylier convey replace, fuel filter replace, spark plugs replace coil pack #2 replace and smoke out put in the car. But it still running sluggish.

Asked by for the 2002 Mercury Grand Marquis
2 answers
ck fuel pump pressure and volumn
agree with greg's auto. also might check the mass air flow sensor.