1997 Ford F-150 Acceleration

I have a 1997 ford f150 with a 1998 ford f150 v6 engine in it, when I put the pedal completely to the floor it doesn't take off, it takes like 4 or 5 seconds for the truck to tsee off. When I put the pedal to the floor it starts going faster but it does it pretty slowly, like I said after about 4 or 5 seconds that's when it takes off. Could it have anything to do with the part in the picture? There's a cable that goes to that, that connects to the butterfly valve on the throttle body, when the throttle is open it pushes the cable. Also do you know what that part is called. Thanks.