Loosen the the screw5/16" socket) at the control panel at the left rear of the engine. Set throttle to full speed and move the cable housing upward; if it works the choke also, move it until the choke is just ready to be engaged. Then tighten the screw to clamp the housing.
You adjust the tappet. That's the thingy that pushes the valve down.
Want to watch the rather "neat" YouTube video? Take the link at the bottom!
Watch this video on YouTube. It will tell you how step by step. http://www.youtube.com/watch?v=NjzX-PUjKmo
It may not be your throttle cable it might be that your governor is stuck.
Try watching the video in the link below:
how do you adjust throttle bodie on 2004 harley
To adjust the throttle on a 1986 Mercedes 300E 6-cylinder, locate the throttle linkage at the engine. Inspect the adjustment screw on the throttle body; turning it clockwise typically increases throttle opening, while counterclockwise decreases it. Ensure the throttle plate is fully closed when the accelerator pedal is not pressed. After adjustments, test the throttle response and ensure proper idle speed is maintained.
Even though an Intek is not shown, it would be the YouTube video below.
You need to either adjust your carburetor richer or leaner while at full throttle.
Have some one professional adjust your TPS (throttle position sensor)
On the driver's side of the F 150 carb, there should be the linkage for the throttle. On the linkage there should be a set screw that you can turn to adjust the engine idle.
The throttle cable is not adjustable.