I have an automatic 68' Camaro. I have a kick down cable installed, but it doesn't work when I am driving it.

 

It may need adjusting in making it work.
First, engine off, manually pull forward of cable to the end and hope you feel some resistance the last 1/4 inch of travel.
Ensure the cable end is installed on the ball stud on bottom of carb arm.
Have an assistant floor the gas pedal and hold.
Check primary throttle ensuring they do open to max, if not, adjust linkage.
Ensure throttle does return to idle after adjustment; if not, fix it.
Hold throttle to floor, at cable bracket, pull out the clip holding the case.
Once clip is out, and with throttle floored, pull back on cable casing removing slack and install clip.
Ensure all slack is gone from cable by pulling cable forward ensuring there is no slack.
If slack is still there, pull back on cable casing with clip ou.
Remove slack, install clip, ensure throttle goes back to idle several times.
Replace air cleaner nd go for a drive.

 

Thanks man, I now only have one issue which is that the pedal doesn't return to idle. It seems to be on around at 5% throttle, and I am not sure how to fix it.

 

Generally, there are two return springs on throttle.
One is the main one in front of the linkage, the larger of the two springs.
The second spring is smaller in size and pull and connects to the bottom of the throttle and the rear top valve cover bolt.