Windstar Idle Air Control Valve

1999 Windstar with 80,000 miles has caused a little trouble with start up. It doesn't bother me because I just give it a little more juice and it usually settles down once it warms up a bit. But mum got stuck in Massachusetts by herself once and that wasn't good. Anyway, the battery died at Windsor Hills and a volunteer named Mike helped diagnose the problem and changed the battery. He even drove to Walmart to get a new one for us. While he was at it, he noticed a slow idle and even stalling. He looked for a vacuum leak and sprayed carb and choke cleaner around the engine to see if a vacuum leak would make the engine run faster. Nothing happened so he said it might be the idle solenoid and I should get a good mechanic to take a look when I got home.
So I called the car parts shop and they said they didn't have such a thing. Then I called Ford and they said what do you mean, tell me where it goes. Then he said do you mean the IAC valve, and I said yes, not wanting to sound like I didn't know what I was talking about. That was about $170. So I called the car parts shop again with the right name, and they said $80.
A quick search on the internet told me to take the thing off and clean it out. So that's what we did. At first I couldn't really see in and we just sprayed in some cleaner. That didn't make any difference, so we took it off again. This time I poked a scribe in the hole and was able to move the piston back so that the valve opened the hole between the two halves. The unit is a little valve that allows air to bypass the normal intake system when the idle is too low, i.e. at start-up. It was stuck closed and that's why the idle was too low when cold, making the engine stall. So we got it unstuck. The car started up and idled properly.
We didn't really do a good job of cleaning it, and it started to stick again. So today we took it off again and soaked it in carb and choke cleaner. We also tried to scrape out the gunk and clean it up better. Hopefully it will stay good now (so we save $80!).
Now the 'check engine' light is on again so we'll have to find out which codes are outstanding. The car automatically fails inspection if the 'check engine' light is on.