1999 Ford Taurus sticky gas pedal

Engine Mechanical problem
1999 Ford Taurus 6 cyl Two Wheel Drive Automatic

Guys,

My girlfriend's car doesn't so much have a sticky gas pedal - because the pedal travels well through its normal range - but the car doesn't respond immediately as you begin pressing the pedal, and then there is a hard leap forward as it begins to move.

Is there a precedence for this kind of problem?

I really want to avoid taking it to a mechanic, because I think this will be one of those very expensive chases to find a simple problem. Do you have any ideas?

Tyler