How do you tighten the throttle cable on a 1997 Mercury Cougar?

I have a 1997 Mercury Cougar that idles fast (1200-1300 RPM in park) almost all the time, for about 5 minutes every 15 minutes it will idle normal (500-700 RPM). I looked at the throttle body and one of the two cables is loose. From what I found on the internet the throttle cable, looking from the passenger side it's the right cable, is the loose one, the other is the cruise control.

How do I tighten the throttle cable to get the slack out of it?
If this isn't the problem what could be?
Any input is appreciated.