2003 V6. Tracction takes its time to get trasmitted?

Hi, About 6 weeks ago I bought a used 2003 Mustang V6 with some 12,000 miles on it.

I wonder if somebody can help with this: When the car is stopped and I I press the gas pedal slighly, I can hear the noise of the engine going up but I don't feel that the wheels are getting any more power. It seems that the engine revs up first and after a fraction of a second the wheels finally get the power. It does not make sense. I am used to hitting the gas pedal and feeling the acceleration right away.

Any ideas??

Thanks

Ed