ISV

For a short while after replacing the intercooler hose everything was peachy. Then our idle became erratic. It would surge to ~2000RPM then drop to ~1000RPM, and sometimes it would oscillate within that range.

From my reading, it became clear the idle stabilizer valve (ISV) was the likely culprit. Thankfully, this was another simple repair.

The ISV is located on the back side of the intake manifold, and is connected to two hoses and an electrical socket. This valve can become dirty over time and will gum up. The repair process was to remove the valve and to clean it out with throttle-body cleaner. Many people make it a point to stress the use of throttle-body cleaner as opposed to carb cleaner, as carb cleaner lacks lubrication. The idea is that if you were to use carb cleaner, this valve could potentially seize up over time. May as well do it right the first time.

Both hoses connected to the ISV are held on by hose clamps, which can be removed with a flat-head screwdriver. Once the hose clamps are loosened, it may take a considerable amount of pulling and twisting to disconnect the hoses from the ISV. The electrical connector has a metal clip that must be depressed while you pull to remove it.

With the ISV removed, simply hose it with throttle-body cleaner until crud stops coming out. You want the cleaner to be coming out clear. It may help to prop the ISV up someplace and let it soak for a while. I left mine sitting for ~20 minutes to soak after the cleaner had begun to come out clear, then sprayed some more in for good measure. Putting things back together should be a straightforward.

A can of throttle-body cleaner is cheap. I can be certain I would have been charged at least $40 for a mechanic to solve my problem, and quite a bit more if they felt it necessary to replace the part. The throttle-body cleaner cost me ~$5, and the whole procedure took no more than half an hour.

Casper now idles steadily at 1000RPM.