IAC valve acting up

I have a suspicion you are getting wrapped around the axle and over-thinking this. First, please elaborate on what "idles like crazy" means. Is the idle speed too fast, too slow, erratic, etc. The sucking noise you are hearing could just be the normal sound heard near the automatic idle speed motor when it opens the valve to get idle speed up. That is usually the result of the Engine Computer trying to overcome a low idle speed caused by something unrelated, like a misfiring cylinder.

Do you have access to a scanner? If you do, look under "Inputs/Outputs, or some similar menu, for actual "idle speed steps" or "desired idle speed steps. That will be a number between 0 and 256. For a properly-running engine, you'll typically find that around step 32. The higher the number, the more the computer is trying to increase idle speed. We will also want to look at if actual idle speed agrees with the step number to tell us if actual idle speed is too high or too low, and whether the computer is trying or not trying to correct it and with or without success.

The idle speed motors have a very low failure rate. They can fail electrically, which is not common because an internal wire would have to break, and these use pretty large wires inside, or it would have to become stuck. If you observe idle speed changing at all, the motor is not stuck. Years ago we had trouble with the air passage becoming plugged with carbon, but that was mainly on the 3.0L engine used in front-wheel-drive minivans and cars. With the better additives in today's gas, we do not see that anymore.

If you remove the motor, you can squeeze really hard to make the pintle valve retract. If you reinstall it that way, idle speed may be too high the next time you start the engine, then it should slowly come down to normal. You can also pull the pintle valve out by hand, but you do have to be pretty strong to do so. You should also see the valve move in and out a little when a helper turns the ignition switch on. The computer has no way of knowing how far that valve is in or out, so when you turn the ignition switch on, it runs the valve fully-out and then some to insure it is fully-closed and it knows where it is starting from, then it opens it roughly fifty steps to give you the nice "idle flare-up to 1,500 rpm at start-up. If you see that movement in the valve, the unit is working.

The part number for the automatic idle speed motor changed a few times over the years as they were improved and if the plug was oriented differently, but they almost all interchanged. One thing you do need to be aware of is the bolts are held in with Lock-Tight. You need a Torx bit to remove the bolts. Be sure to use the correct size and that it is fully seated, to prevent stripping the holes and rounding them out.

Two things come to mind to check for. First is a misfire causing the rough running. Next is a vacuum leak. That will cause a high idle speed without a corresponding increase in power. If you can get hold of a scanner to look at the idle steps I described, you will find it at "0" if there is a vacuum leak. The computer is trying to lower idle speed, but without success. The automatic idle speed motor is actually a carefully-controlled, very precise vacuum leak controlled by the computer. That computer does not have control over some other unintentional vacuum leak.

A misfire will cause idle speed to be too low. The result will be higher idle step than normal, ... Say around 50 or even higher. At a Jeep school I attended about twelve years ago, the instructor was showing us how much control over idle speed the Engine Computer has. He disabled one injector on a V-8 engine. Idle steps went up to around "50". He kept disabling more and more injectors until he finally had six disconnected. The engine still ran at the correct idle speed on just two working cylinders, but the idle steps were not even up to 200 yet. Obviously it did not run well at all, but it did run.

To add to the confusion, if you have a misfire that results in a lower idle speed, and a vacuum leak that results in a higher idle speed, the computer is going to lose its mind trying to keep the idle speed correct. Besides checking for cracked and dry-rotted vacuum hoses, check if your engine uses an EGR valve. Those are never supposed to open at lower engine speeds, but if the valve is blocked open by a chip of carbon, exhaust gas will enter the cylinders all the time. That commonly shows up as severe rough running at idle, but you usually will not notice it at highway speeds. As a test, you can slide a thin strip of sheet metal under the valve to block the ports. If that solves a symptom, you can try cleaning the valve, but replacement is the better solution.

I do not have a comment of value on the positioning of the crankshaft position sensor. Its air gap is critical for proper operation. Some other engines use a thick paper spacer on the end to set that air gap. Yours uses a differently-shaped mounting bracket that sets the depth for the sensor, and it cannot be set wrong, as long as its bolted down solidly.