I drive a 2005 ford fiesta zetec. Why when I accelerate, does my car hesitate before building up speed?

I drive a 2005 ford fiesta zetec. Why when I accelerate, does my car hesitate before building up speed?

I had the same problem on my 2012 Fusion for a while. They said it is normal when the weather changes. If your car sits in the cold for a while before use, make sure to give it time to warm up a bit!