I've had my VX since it had around 30,000 miles on it and I'm the 2nd owner. I got that dreaded code & CEL sometime after that... can't remember when, but must have been after 100,000 miles, since I bought an extended aftermarket warranty & would have taken it it otherwise.

So the light comes on shortly after 100,000 miles & stays on... at first it would go off on it's own, but then return. This happened a few times & then it just stayed on. I replaced the EGR once and it stayed off for a few months. Then back on. I finally just accepted it & lived with it for years...

Then this past fall I developed a REALLY high idle. At first it jumped to around 1200RPM or so, & over the course of a couple of weeks, it had progressed to around 3200-3400RPM. Bad news for winter driving, since it wanted to push me instead of letting me stop. (Also VERY harsh engagement into Drive!)

So this past winter with over 200,000 miles on the clock, I replaced the lower intake gasket to fix the vacuum leak that was giving me the HIGH idle. (2nd time I've replaced that due to vacuum leaks, but the first time I didn't have a high idle at all... if I remember right it was just running a little rough.) Anyway - I put it all back together & fire it up and to my dismay, the idle was STILL high... Although lower than it had been. It was still around 2500 or so. Crap. This is great. I revved it. I drove it. I shut it down... Next time I started it up it was a little lower... Then it was lower again. By the end of the next day, my idle had returned to normal & it was running like a champ again. I think that since it was so bad, for so long that the computer had to relearn and adjust over a few start / run cycles.

The point of my story is this. This time when I replaced the lower intake manifold, I realized that in the process of doing so, I had previously allowed the right, rear corner of the intake rest on the gasket while I was trying to re-position things; struggling with a fuel line bracket or something back there that makes this step a PITA. Anway - I think that when this happened before, that it left an indention in the gasket which still allowed a small leak, that eventually let go and developed a large leak that led to my high idle. Since replacing the gasket this past winter, my light went off & has stayed off for nearly 10,000 miles!

Also, before the idle found it's way back to normal, I did a few other things. I carb cleaned the heck out of the MAF (in the air-intake tube), as well as taking the IAC motor off carb cleaning it out thoroughly too...

Might be something worth looking into.