2nd cable is the cruise control. Goes to a round thing under the hood.
AMC is right... you need to find out what is causing your idle problem and not adjust the idle. The screws you see on the throttle linkage are not for adjusting idle- but you can make the idle go up using one if you want. It will cause other issues though, and if someone else has already turned those screws and you want it to go back to being right, then read up. Those are actually the throttle plate stop screws. It's a way to stop the throttle plate mechanically without it wearing out the spot inside the throttle body. Remove the air intake so you can get to the throttle plate. Loosen the throttle plate stop screw until the plate rests on the throttle stop. Now using your finger or something like a pencil to rest against the throttle plate, slowly turn the screw down until you feel the plate move. As soon as you feel the plate start to move- stop.
Now, time to fix the idle. The best way IMO, is to do a "tune-up", and clean the IAC. Remove the IAC, clean the plunger with a Q-tip, and make sure that the 2 chambers are sealed. If there is damage to the sealing surface, or the plunger top is not sealing things up- get a new one. The plunger can be pushed in very easily with the Q-tip. If it offers any resistance, get a new one. Otherwise, clean and re-install.
-Change plug boots if those haven't been done.
-Replace fuel filter following the correct procedure to discharge the fuel pressure by disconnecting the fuel cutoff switch, then attempting to start the vehicle. Do not remove the white clip, press it in, and wiggle to disconnect. One will be backwards so you can't reach it, follow the line back towards the fuel tank, and 6" away you'll see an easy to reach clip. Disconnect that. Don't lie directly beneath the fuel filter- you don't want gasoline in your eyes. Just in case of an accident, I keep a bottle of lukewarm water filtered nearby when I change the fuel filter. A single 5/16 or 8mm screw holds the fuel filter bracket in place.
-Remove the MAF sensor. Clean with MAF spray cleaner. Don't stick the straw in too far.
-Disconnect the negative battery terminal for 10 mins or so. Reconnect. When you start the car, do not touch the accelerator. Allow the engine to idle for 10 mins. You'll notice slight fluctuations in the idle. That is normal. The ECU is testing for the optimal A/F ratio and resetting the idle. It is supposed to only take 5 mins, but it's hard to tell when that 5 mins starts. You'll know when it's done because the idle will drop from 1k, to closer to 800 where it should be.
Also, once it is idling right, check the air cleaner if you still have the factory air cleaner installed. The procedure is in the owner's manual, but I think you just press the yellow TEST button under the hood behind the driver's side headlight, and hold it for a few seconds until it stops moving. If the air cleaner is bad, you'll need to find a replacement- we can make suggestions for any budget.