This was happening to my Contour. I cleaned the MAF (Mass Airflow Sensor) and that took care of the hesitation issue. I spoke with my cousin (a certified Ford Tech) and as soon as I described the issue, just like yours, he said it was the MAF 90%, plugs and wires 10%. Cleaning/replacing my MAF fixed that issue, but now I have an issue where my car will be on the verge of stalling for the first two minutes of cold starting. I am going to replace the plugs and wires this weekend. I will let you know how it goes.
